{ "name": "interventions", "description": "The Intervention Database: depth, evidence grade, mechanism, cost data.", "license": "CC BY 4.0. Cite “Charitology (charitology.org)”.", "generated": "2026-10-26", "data": [ { "id": "cash-transfers", "path": "/record/interventions/cash-transfers/", "title": "Unconditional cash transfers", "summary": "Giving money directly to people living in poverty, with no conditions on how they spend it.", "depth": 1, "evidence": "strong", "mechanism": "Cash lets each household buy what it needs most, from food to school costs to a metal roof or livestock. Money spent in local shops and markets also raises the incomes of neighbors and local businesses.", "causes": [ "extreme-poverty" ], "timeToEffect": "immediate", "durability": "years", "feedback": "some", "agency": "community-led", "conditions": [ "missing-voice", "missing-feedback-loop" ], "sources": [ { "title": "General Equilibrium Effects of Cash Transfers: Experimental Evidence from Kenya", "url": "https://www.econometricsociety.org/publications/econometrica/2022/11/01/General-Equilibrium-Effects-of-Cash-Transfers-Experimental-Evidence-from-Kenya", "publisher": "Egger, Haushofer, Miguel, Niehaus and Walker, Econometrica 90(6)", "year": 2022 }, { "title": "Improving Economic and Psychological Well-being through Unconditional Cash Transfer in Kenya (evaluation summary)", "url": "https://www.povertyactionlab.org/evaluation/improving-economic-and-psychological-well-being-through-unconditional-cash-transfer", "publisher": "J-PAL" }, { "title": "Giving directly to support poor households (scale-up summary)", "url": "https://www.povertyactionlab.org/scale-ups/unconditional-cash-transfers", "publisher": "J-PAL", "year": 2025 }, { "title": "Unconditional Cash Transfers: A Bayesian Meta-Analysis of Randomized Evaluations in Low and Middle Income Countries", "url": "https://nber.org/papers/w32779", "publisher": "Crosta, Karlan, Ong, Rüschenpöhler and Udry, NBER Working Paper 32779", "year": 2024, "note": "Working paper, revised in 2026." }, { "title": "GiveWell’s Criteria for Top Charities", "url": "https://www.givewell.org/how-we-work/criteria", "publisher": "GiveWell" } ], "review": "draft", "body": "## What the evidence says\n\nCash is one of the most studied antipoverty tools. A 2024 meta-analysis, still a working paper, pooled 115 studies of 72 programs in low- and middle-income countries. It found clear positive average effects on 10 of 13 outcomes, including consumption, income, food security, psychological well-being, assets, school enrollment and labor supply.\n\nThe best-known trials are in Kenya. In an early randomized evaluation of GiveDirectly’s transfers, recipients’ monthly consumption rose 23 percent, their assets rose 61 percent, and their psychological well-being improved. Spending on alcohol and tobacco did not rise, and the study found no effects on health or education measures. Three years later, recipients still held about 43 percent more assets than the comparison group, but the gains in consumption and well-being were no longer evident.\n\nA larger study tested what cash does to a local economy. Egger and colleagues (2022) gave about $1,000 each to more than 10,500 poor households across 653 villages, an injection worth more than 15 percent of local GDP. Recipients gained, and so did neighbors who received nothing and local firms, with minimal price inflation. The authors estimate a local multiplier of 2.5: total local economic activity rose by about two and a half times the amount transferred.\n\nThe grade here is for short-run gains in consumption, assets and well-being, where many rigorous studies agree. Evidence on gains lasting many years is thinner.\n\n## Where it sits on the depth scale\n\nCharitology places cash at **repair** (depth 1), with part of it at relief. Some of each transfer meets needs today. Some rebuilds a household’s base, such as a roof or livestock, which in Kenya was still there three years later. Cash moves money through an economy, but on its own it doesn’t change the laws, markets or institutions that produce poverty, which is where depth 3 work acts. A government cash program built permanently into social protection would sit closer to structure.\n\nCash is also unusual in who steers it. The program decides who is eligible, but recipients decide how the money is used, which speaks directly to [the Missing Voice](/diagnosis/missing-voice/).\n\n## Open questions\n\n- Which gains last, and for how long? In Kenya, assets persisted while consumption gaps faded. In the three-year follow-up, researchers could not tell whether remaining differences between recipients and their neighbors reflected recipients’ gains or neighbors’ losses.\n- What is the choice itself worth to the people who receive it? That is [the agency premium](/open-problems/the-agency-premium/).\n- No reliable per-dollar estimate of the kind the [Impact Calculator](/tools/impact-calculator/) uses is published for cash. Its benefits are usually measured as consumption gained, and GiveWell uses cash as the benchmark it compares other programs against." }, { "id": "community-health-workers", "path": "/record/interventions/community-health-workers/", "title": "Community health workers", "summary": "Local people trained to offer basic health services and advice in their own communities, from promoting vaccination and breastfeeding to referring sick children to clinics.", "depth": 2, "evidence": "moderate", "mechanism": "A trained member of the community visits homes, gives health advice, hands out or sells basic health products and refers the sick to clinics. Help comes to the household instead of waiting for the household to reach a clinic.", "causes": [ "global-health" ], "timeToEffect": "months", "durability": "while funded", "feedback": "some", "agency": "top-down", "conditions": [ "missing-voice", "short-horizon" ], "sources": [ { "title": "Lay health workers in primary and community health care for maternal and child health and the management of infectious diseases (Cochrane systematic review)", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6485809/", "publisher": "Lewin and colleagues, Cochrane Database of Systematic Reviews", "year": 2010 }, { "title": "Reducing Child Mortality in the Last Mile: Experimental Evidence on Community Health Promoters in Uganda", "url": "https://www.aeaweb.org/articles?id=10.1257/app.20170201", "publisher": "Björkman Nyqvist, Guariso, Svensson and Yanagizawa-Drott, American Economic Journal: Applied Economics 11(3)", "year": 2019 }, { "title": "Community Health Provision at Scale: Evidence from a Randomized Trial in Uganda (seminar abstract)", "url": "https://www.nhh.no/en/calendar/fair/2023/fair-seminar/martina-bjorkman/", "publisher": "Martina Björkman Nyqvist, FAIR Seminar, NHH Norwegian School of Economics", "year": 2023 }, { "title": "WHO guideline on health policy and system support to optimize community health worker programmes", "url": "https://www.who.int/publications/i/item/9789241550369", "publisher": "World Health Organization", "year": 2018 } ], "review": "draft", "body": "## What the evidence says\n\nA 2010 Cochrane review of 82 studies of lay health workers, 55 of them in high-income countries, found moderate-quality evidence that they increase childhood immunization (risk ratio 1.22) and breastfeeding. It found low-quality evidence that they may reduce child deaths: the estimate was a 25 percent reduction, but its confidence interval included no effect.\n\nA randomized trial in Uganda found a large effect on child deaths. Locally recruited health promoters received incentives to visit homes, teach health behaviors, give medical advice and referrals, and sell preventive and curative products. After three years, under-five mortality was 27 percent lower in program villages, at an estimated $68 per life-year saved.\n\nA later trial in Uganda, presented at a 2023 research seminar, tested two programs at scale. The trial design let researchers review results midway and change course. One program was redesigned and the trial extended by two years. Among children fully exposed to the revised version, under-five mortality fell by 29 percent. The other showed no significant difference in child mortality. The idea alone doesn’t guarantee results: design and management vary, and so do outcomes.\n\nWHO’s 2018 guideline on community health worker programs covers how to educate, deploy and manage them and how to fit them into the wider health system.\n\nThe grade is moderate. Several trials show gains in vaccination and breastfeeding, and the evidence on deaths is promising but less consistent. The $68 figure comes from one trial of one model, and these programs vary too much for one number to stand for the whole category, so this entry has no Impact Calculator figure.\n\n## Where it sits on the depth scale\n\nMost of this work is **prevention** (depth 2): vaccination, breastfeeding and products that keep children from getting sick. Some of it is relief, such as caring for or referring a child who is already ill. When a government builds community health workers into its health system and budget, the work moves toward structure.\n\n## Open questions\n\n- Who should pay community health workers, and what happens to a program when its grant ends? See [the government question](/open-problems/the-government-question/) and [the Short Horizon](/diagnosis/short-horizon/).\n- Most studies in the Cochrane review came from high-income countries. How well do their results carry over to poorer ones?\n- These workers come from the communities they serve. How much say do those communities have in what the programs do? See [the Missing Voice](/diagnosis/missing-voice/)." }, { "id": "corporate-animal-welfare-campaigns", "path": "/record/interventions/corporate-animal-welfare-campaigns/", "title": "Corporate animal welfare campaigns", "summary": "Advocacy that persuades food companies to change what they buy, such as pledging to source only cage-free eggs, and then tracks whether they follow through.", "depth": 3, "evidence": "weak", "mechanism": "Retailers, restaurants and food service companies buy from many farms. The theory is that when these buyers commit to new standards, their suppliers change how animals are housed to keep the business, and public tracking keeps pressure on companies to meet their deadlines.", "causes": [ "animals" ], "timeToEffect": "years", "durability": "years", "feedback": "some", "agency": "top-down", "conditions": [ "measurement-gap", "single-lens" ], "sources": [ { "title": "Corporate campaigns affect 9 to 120 years of chicken life per dollar spent", "url": "https://rethinkpriorities.org/research-area/corporate-campaigns-affect-9-to-120-years-of-chicken-life-per-dollar-spent", "publisher": "Saulius Šimčikas, Rethink Priorities", "year": 2019 }, { "title": "Global Cage-Free Egg Fulfillment Rate Jumps to 92%", "url": "https://thehumaneleague.org/article/2025-cage-free-fulfillment-report", "publisher": "The Humane League, reporting the Open Wing Alliance’s progress report", "year": 2025 }, { "title": "Growing share of egg-laying hens are cage-free (Chart of Note)", "url": "https://ers.usda.gov/data-products/charts-of-note/107564", "publisher": "USDA Economic Research Service", "year": 2023 }, { "title": "EFSA: alternatives to cages recommended to improve broiler and hen welfare", "url": "https://www.efsa.europa.eu/en/news/efsa-alternatives-cages-recommended-improve-broiler-and-hen-welfare", "publisher": "European Food Safety Authority", "year": 2023 }, { "title": "Laying hen mortality in different indoor housing systems: a meta-analysis of data from commercial farms in 16 countries", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7862694/", "publisher": "Schuck-Paim, Negro-Calduch and Alonso, Scientific Reports 11", "year": 2021 } ], "review": "draft", "body": "## What the evidence says\n\nEach link in the chain has different evidence.\n\n**Commitments.** Campaigns have won many. More than 2,750 companies have made cage-free egg commitments, according to The Humane League, an animal advocacy group.\n\n**Follow-through.** A progress report from the Open Wing Alliance, published by The Humane League, says 92 percent of cage-free commitments with deadlines of 2024 or earlier had been fulfilled as of July 2025, up from 89 percent a year before. That figure counts commitments, not hens, and comes from advocates’ own reporting. In the United States, USDA data show the cage-free share of the egg-laying flock rising from 36 percent in January to 38 percent in June 2023. USDA credits both state laws banning hen confinement and corporate pledges, so the campaigns’ share of the change can’t be read from the trend.\n\n**Welfare.** In 2023 the European Food Safety Authority’s scientists recommended avoiding cages for laying hens and broiler chickens. A common worry is that cage-free flocks die at higher rates. A meta-analysis of 6,040 commercial flocks, about 176 million hens in 16 countries, found mortality fell as producers gained experience with cage-free systems and found no difference between caged and cage-free systems in recent years.\n\n**Cost-effectiveness.** Rethink Priorities estimated in 2019 that the corporate chicken welfare commitments won from 2005 to 2018 will affect 9 to 120 years of chicken life per dollar spent. That is a subjective range for past spending, not a forecast for a new dollar, and it rests on assumptions about follow-through and about how many hens would have gone cage-free anyway. Because the figure is not a cost per outcome in the sense the Impact Calculator uses, this entry has none.\n\nThe grade is weak because Charitology found no rigorous test of the central causal claim, that campaigns put more hens in better housing than would otherwise have happened. The claim rests on tracking data, trends with several causes and modeling.\n\n## Where it sits on the depth scale\n\nThese campaigns are **structure** (depth 3). They change the purchasing rules of large companies, and through them the standards of a whole supply chain, so the harm stops being produced for the animals affected. Whether the change lasts depends on enforcement, which is why follow-through tracking is part of the work.\n\n## Open questions\n\n- How should the welfare of a hen be weighed against other outcomes? See [how much animals count](/record/disagreements/how-much-do-animals-count/) and [the exchange rate problem](/open-problems/the-exchange-rate-problem/).\n- How much of the shift to cage-free would have happened through state laws and market trends alone?\n- Do companies that miss deadlines eventually comply, quietly drop their pledges, or neither?" }, { "id": "deworming", "path": "/record/interventions/deworming/", "title": "Mass deworming", "summary": "Treating all children in places where intestinal worms are common with cheap deworming pills, without testing each child first.", "depth": 2, "evidence": "mixed", "mechanism": "Pills clear existing worm infections. Treating whole schools or communities can also cut how much infection spreads to untreated children. The hoped-for results are better health and school attendance in childhood and higher earnings in adulthood.", "causes": [ "global-health", "education" ], "timeToEffect": "years", "durability": "unknown", "feedback": "weak", "agency": "top-down", "conditions": [ "measurement-gap" ], "sources": [ { "title": "Public health deworming programmes for soil-transmitted helminths in children living in endemic areas (Cochrane systematic review)", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6737502/", "publisher": "Taylor-Robinson, Maayan, Donegan, Chaplin and Garner, Cochrane Database of Systematic Reviews", "year": 2019 }, { "title": "Mass deworming to improve developmental health and wellbeing of children in low-income and middle-income countries: a systematic review and network meta-analysis", "url": "https://doi.org/10.1016/S2214-109X(16)30242-X", "publisher": "Welch and colleagues, The Lancet Global Health 5(1)", "year": 2017 }, { "title": "Worms: Identifying Impacts on Education and Health in the Presence of Treatment Externalities", "url": "https://www.econometricsociety.org/publications/econometrica/2004/01/01/worms-identifying-impacts-education-and-health-presence", "publisher": "Edward Miguel and Michael Kremer, Econometrica 72(1)", "year": 2004 }, { "title": "Twenty-year economic impacts of deworming", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC8040658/", "publisher": "Hamory, Miguel, Walker, Kremer and Baird, PNAS 118(14)", "year": 2021 }, { "title": "Re-analysis of health and educational impacts of a school-based deworming programme in western Kenya: a pure replication", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC4681107/", "publisher": "Aiken, Davey, Hargreaves and Hayes, International Journal of Epidemiology 44(5)", "year": 2015 }, { "title": "Population deworming every 6 months with albendazole in 1 million pre-school children in north India: DEVTA, a cluster-randomised trial", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC3647147/", "publisher": "Awasthi and colleagues, The Lancet 381(9876)", "year": 2013 }, { "title": "Combination Deworming (Mass Drug Administration Targeting Both Schistosomiasis and Soil-Transmitted Helminths)", "url": "https://www.givewell.org/international/technical/programs/deworming", "publisher": "GiveWell", "year": 2025 }, { "title": "Deworming might have huge impact, but might have close to zero impact", "url": "https://blog.givewell.org/2016/07/26/deworming-might-huge-impact-might-close-zero-impact/", "publisher": "GiveWell Blog", "year": 2016 }, { "title": "Soil-transmitted helminth infections (fact sheet)", "url": "https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections", "publisher": "World Health Organization", "year": 2023 } ], "review": "draft", "body": "## What the evidence says\n\nRigorous studies disagree, so this entry is graded **mixed**. The full debate is in the [Disagreement Register](/record/disagreements/deworming-long-run-effects/).\n\nWHO estimates that 1.5 billion people, about 24 percent of the world, carry soil-transmitted worms, and it recommends periodic treatment of at-risk people without individual diagnosis. In 2021, more than 500 million children were treated.\n\nThe case for large benefits rests mainly on one program. Starting in 1998, a school deworming project in Busia, Kenya, phased treatment into 75 schools at random. Miguel and Kremer (2004) reported that absenteeism fell by about a quarter in treated schools, that untreated children nearby also benefited, and that test scores did not improve. A 2021 analysis reported about 14 percent higher consumption when pooling the 15- and 20-year follow-ups, and about 13 percent higher hourly earnings when pooling the 10-, 15- and 20-year follow-ups. These estimates, comparing people who had received two to three more years of treatment, were significant only at the 10 percent level; they were not both estimates from the 20-year follow-up alone.\n\nThe case against comes from systematic reviews. A 2019 Cochrane review of 51 trials concluded that mass deworming does not appear to improve height, hemoglobin, cognition, school performance or mortality. A 2017 review by Welch and colleagues found little to no effect on weight, height, cognition, attendance or mortality, and judged long-run evidence too weak to draw conclusions. The DEVTA trial of about 1 million preschool children in India found no significant effect on deaths or weight.\n\nIn 2015 independent researchers reanalyzed the Kenya data. After coding errors were corrected, they found little evidence that attendance rose in neighboring schools, while effects inside treated schools were largely unchanged. The original authors replied that the corrected data still support their findings.\n\nGiveWell treats deworming as a bet. In 2016 it wrote that most of its staff thought deworming more likely than not to have very little or no impact, but that low costs, about $0.50 to $1 per person treated, keep its expected value high even after applying a 1 to 2 percent multiplier to the trial effects. Because the size of the benefit is the thing in dispute, no reliable per-dollar estimate of the outcome is published, and this entry has no Impact Calculator figure.\n\n## Where it sits on the depth scale\n\nDeworming is **prevention** (depth 2). It clears infections and lowers transmission for a time, but treatment has to be repeated. WHO pairs it with hygiene education and better sanitation, the work that would cut transmission closer to its source.\n\n## Open questions\n\n- Can large long-run gains exist when short-run health gains are hard to detect?\n- GiveWell notes that infections in Busia were much heavier than in most places deworming happens today. Do the results carry over? See [the replication rate](/open-problems/the-replication-rate/)." }, { "id": "food-banks", "path": "/record/interventions/food-banks/", "title": "Food banks and food pantries", "summary": "Collecting donated and purchased food and handing it out, through pantries and meal programs, to households that don’t have enough to eat.", "depth": 0, "evidence": "moderate", "mechanism": "Food banks gather donated and purchased groceries and pass them to local pantries and meal programs, which hand them to households that need food now.", "causes": [ "hunger", "community" ], "timeToEffect": "immediate", "durability": "while funded", "feedback": "weak", "agency": "top-down", "conditions": [ "symptom-trap", "proximity-pull" ], "sources": [ { "title": "The Role of Food Banks in Addressing Food Insecurity: A Systematic Review", "url": "https://doi.org/10.1007/s10900-015-0147-5", "publisher": "Bazerghi, McKay and Dunn, Journal of Community Health 41(4)", "year": 2016 }, { "title": "The Nutritional Quality of Food Provided from Food Pantries: A Systematic Review of Existing Literature", "url": "https://doi.org/10.1016/j.jand.2016.08.015", "publisher": "Simmet, Depa, Tinnemann and Stroebele-Benschop, Journal of the Academy of Nutrition and Dietetics 117(4)", "year": 2017 }, { "title": "A novel food pantry program: food security, self-sufficiency, and diet-quality outcomes", "url": "https://doi.org/10.1016/j.amepre.2013.06.012", "publisher": "Martin, Wu, Wolff, Colantonio and Grady, American Journal of Preventive Medicine 45(5)", "year": 2013 }, { "title": "Food insecurity in U.S. households, 2023 (Chart of Note)", "url": "https://www.ers.usda.gov/data-products/charts-of-note/109859", "publisher": "USDA Economic Research Service", "year": 2024 }, { "title": "SNAP Facts", "url": "https://www.feedingamerica.org/snapfacts", "publisher": "Feeding America" } ], "review": "draft", "body": "## What the evidence says\n\nFood banks can claim one outcome with confidence: people get food when they need it. In 2023, 13.5 percent of U.S. households, about 18 million, were food insecure at some point in the year, and 5.1 percent had very low food security. A 2016 systematic review of 35 publications concluded that food banks play an important role in meeting immediate, severe food needs.\n\nThe same review found that food banks do little to improve food security overall, the steadier measure of whether a household reliably has enough to eat. Their supply is often too small and short of nutrient-dense foods such as dairy, vegetables and fruit. A 2017 review of nine studies of pantry food bags found nutritional quality varied widely and that dairy, vitamins A and C and calcium were especially scarce.\n\nRigorous comparisons are rare. Charitology found no randomized trial comparing pantry access with no access, which would be hard to run ethically. A randomized trial has compared pantry models. Adults recruited from traditional pantries and assigned to Freshplace, a client-choice pantry with monthly coaching and referrals to other services, were less than half as likely to have very low food security over a year than adults receiving standard food bags, and ate about one more serving of fruits and vegetables a day.\n\nCharitology grades the evidence moderate for the outcome food banks claim, immediate relief: the research agrees, though Charitology found few randomized studies. The evidence on longer-term food security is weak, and that is not mainly what food banks set out to change. Charitology has not found a reliable per-dollar estimate of outcomes, so this entry has no Impact Calculator figure.\n\n## Where it sits on the depth scale\n\nFood banks are **relief** (depth 0). They meet the need today, and the need returns tomorrow. That is not a criticism: someone has to make sure people eat while other work goes on. Feeding America, a national network of food banks, says that for every meal its network provides, SNAP, the federal nutrition program, provides nine, and that charitable food alone cannot meet the need. Public programs and the economy around them are where the structural layer sits.\n\n## Open questions\n\n- How many pantry users would otherwise go hungry, and how many would find food another way? Charitology has not found a good estimate.\n- Can pantries that add choice, coaching and referrals act deeper on the depth scale? Freshplace suggests they might. See [symptoms and sources](/record/encyclopedia/symptoms-and-sources/).\n- What share of all giving goes to relief like this? That is [the depth census](/open-problems/the-depth-census/)." }, { "id": "housing-first", "path": "/record/interventions/housing-first/", "title": "Housing First", "summary": "Giving people who are homeless, often with serious mental illness, a permanent home quickly, without first requiring them to accept treatment or stop using substances.", "depth": 1, "evidence": "strong", "mechanism": "The home comes first, and it does not depend on treatment or sobriety. Rent support pays for the housing, and case managers or treatment teams offer help alongside it, on the theory that a stable home makes recovery and everything else easier.", "causes": [ "housing", "mental-health" ], "timeToEffect": "immediate", "durability": "while funded", "feedback": "some", "agency": "co-designed", "conditions": [ "symptom-trap" ], "sources": [ { "title": "Effectiveness of interventions to reduce homelessness: a systematic review and meta-analysis (Campbell systematic review)", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC8427990/", "publisher": "Munthe-Kaas, Berg and Blaasvær, Campbell Systematic Reviews 14(1)", "year": 2018 }, { "title": "Effects of Housing First approaches on health and well-being of adults who are homeless or at risk of homelessness: systematic review and meta-analysis of randomised controlled trials", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6581117/", "publisher": "Baxter, Tweed, Katikireddi and Thomson, Journal of Epidemiology and Community Health 73(5)", "year": 2019 }, { "title": "A Multiple-City RCT of Housing First With Assertive Community Treatment for Homeless Canadians With Serious Mental Illness", "url": "https://doi.org/10.1176/appi.ps.201400587", "publisher": "Aubry and colleagues, Psychiatric Services", "year": 2016 }, { "title": "Effect of scattered-site housing using rent supplements and intensive case management on housing stability among homeless adults with mental illness: a randomized trial", "url": "https://doi.org/10.1001/jama.2015.1163", "publisher": "Stergiopoulos and colleagues for the At Home/Chez Soi Investigators, JAMA 313(9)", "year": 2015 } ], "review": "draft", "body": "## What the evidence says\n\nOn its main outcome, keeping people housed, the evidence is strong. A 2019 meta-analysis of four randomized trials in Canada and the United States, with about 3,410 adults, found that Housing First participants were about two and a half times as likely to be stably housed after 18 to 24 months (risk ratio 2.46). A 2018 Campbell review of 43 randomized trials of homelessness programs, 37 of them in the United States, found that housing without an abstinence requirement probably adds about 110 days of stable housing compared with usual services, with moderate certainty.\n\nCanada’s At Home/Chez Soi trial ran in several cities. Among people with high support needs, Housing First participants spent 71 percent of their time in stable housing, compared with 29 percent of those receiving usual services. For people with moderate needs, rent supplements plus intensive case management also increased housing stability over two years.\n\nOther outcomes are less clear. The 2019 meta-analysis found no clear differences in mental health, physical health or substance use, though problem substance use fell in both groups. Housing First participants made fewer emergency department visits and had fewer hospital admissions. The At Home/Chez Soi trial for people with moderate needs found no difference in quality of life. All four trials in the meta-analysis were judged at high risk of bias, and follow-up was limited to about two years.\n\nThe grade is strong for housing stability. Reviewers flag risks of bias, such as poor reporting and the lack of blinding, but the housing effect is large and consistent across trials. For health and well-being, the evidence is weak or mixed. Charitology has not found a reliable published cost per outcome that would fit the Impact Calculator.\n\n## Where it sits on the depth scale\n\nHousing First as tested is **repair** (depth 1). It restores a home to a person who has lost one, quickly and without preconditions. It doesn’t change the housing supply, prices or other rules that produce homelessness. When a government adopts Housing First as the organizing rule of its whole homelessness system, the policy acts closer to structure, but that is a different claim from what the trials measured.\n\n## Open questions\n\n- What happens after two years? Few trials follow people longer.\n- Most of the evidence comes from North America. How well does it travel?\n- Housing First keeps people housed while it is funded. What would it take to stop people losing homes in the first place? That is the [Symptom Trap](/diagnosis/symptom-trap/) in a single program, and part of [the government question](/open-problems/the-government-question/)." }, { "id": "insecticide-treated-nets", "path": "/record/interventions/insecticide-treated-nets/", "title": "Insecticide-treated bed nets", "summary": "Nets treated with insecticide, hung over beds, that protect sleepers from the mosquitoes that carry malaria.", "depth": 2, "evidence": "strong", "mechanism": "The net blocks mosquitoes while people sleep, and the insecticide kills mosquitoes that land on it, which also lowers malaria risk for people nearby.", "causes": [ "global-health" ], "timeToEffect": "immediate", "durability": "years", "feedback": "some", "agency": "top-down", "cost": { "outcome": "death averted (GiveWell’s modeled range for the places where it funds net campaigns)", "low": 3000, "high": 8000, "asOf": "December 2023 cost-effectiveness analysis", "source": { "title": "Mass Distribution of Insecticide-Treated Nets (ITNs)", "url": "https://www.givewell.org/international/technical/programs/insecticide-treated-nets", "publisher": "GiveWell", "year": 2023 }, "note": "This is a model for net campaigns in the locations GiveWell funds, not a measured price for a life. The range varies by location and depends on malaria mortality, net use, how long nets last and what other funders would have paid for." }, "conditions": [ "story-bias" ], "sources": [ { "title": "Mass Distribution of Insecticide-Treated Nets (ITNs)", "url": "https://www.givewell.org/international/technical/programs/insecticide-treated-nets", "publisher": "GiveWell", "year": 2023 }, { "title": "Insecticide-treated nets for preventing malaria (Cochrane systematic review)", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6418392/", "publisher": "Joseph Pryce, Marty Richardson and Christian Lengeler, Cochrane Database of Systematic Reviews", "year": 2018 } ], "review": "draft", "body": "## What the evidence says\n\nBed nets are among the most studied interventions in global health. A 2018 Cochrane review pooled five randomized trials with more than 200,000 participants. It found that, compared with no nets, insecticide-treated nets cut child deaths from all causes by about 17 percent, which works out to roughly 5.6 lives saved each year for every 1,000 children protected. The reviewers rated that evidence high-certainty.\n\n## Where it sits on the depth scale\n\nNets are **prevention** (depth 2): they stop malaria for the people under them, and they keep working only while nets are replaced. They don’t change the conditions that let malaria persist, such as weak health systems or mosquito habitats. That is not a criticism. Prevention at this scale saves lives now, while structural work goes on.\n\n## Open questions\n\n- Insecticide resistance in mosquitoes is spreading, and newer nets use different chemicals. How long today’s effect sizes hold is an active research question.\n- How nets are used day to day varies by place and season, which is why distribution programs track usage as well as delivery." }, { "id": "lead-exposure-elimination", "path": "/record/interventions/lead-exposure-elimination/", "title": "Lead exposure elimination", "summary": "Regulation and advocacy to take lead out of paint, fuel and everyday products, so that children and adults stop being exposed to it.", "depth": 3, "evidence": "moderate", "mechanism": "Lead harms the brain and heart, and there is no known safe level. A law that bans lead in a product stops new exposure from that source for everyone, without anyone having to change their own behavior. Advocacy groups test products for lead, publish the results and press governments to pass and enforce such laws.", "causes": [ "global-health" ], "timeToEffect": "years", "durability": "generations", "feedback": "weak", "agency": "top-down", "conditions": [ "symptom-trap", "measurement-gap" ], "sources": [ { "title": "Lead poisoning (fact sheet)", "url": "https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health", "publisher": "World Health Organization", "year": 2026 }, { "title": "Global health burden and cost of lead exposure in children and adults: a health impact and economic modelling analysis", "url": "https://doi.org/10.1016/S2542-5196(23)00166-3", "publisher": "Larsen and Sánchez-Triana, The Lancet Planetary Health 7(10)", "year": 2023 }, { "title": "Blood Lead Levels in U.S. Children Ages 1–11 Years, 1976–2016", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7969125/", "publisher": "Egan, Cornwell, Courtney and Ettinger, Environmental Health Perspectives 129(3)", "year": 2021 }, { "title": "Era of leaded petrol over, eliminating a major threat to human and planetary health", "url": "https://unep.org/news-and-stories/press-release/era-leaded-petrol-over-eliminating-major-threat-human-and-planetary", "publisher": "UN Environment Programme", "year": 2021 }, { "title": "Examination of lead concentrations in new decorative enamel paints in four countries with different histories of activity in lead paint regulation", "url": "https://doi.org/10.1016/j.envres.2014.03.006", "publisher": "Clark and colleagues, Environmental Research 132", "year": 2014 }, { "title": "How Cost-Effective Is LEEP’s Malawi Program?", "url": "https://leadelimination.org/malawi_cost-effectiveness_intro/", "publisher": "Lead Exposure Elimination Project", "year": 2022 } ], "review": "draft", "body": "## What the evidence says\n\nThe harm is well established. WHO says there is no known safe blood lead level. Citing the Global Burden of Disease study, it attributes more than 3.5 million deaths in 2023 to lead, mostly through heart and blood vessel disease. Other estimates run higher: Larsen and Sánchez-Triana (2023) put lead-linked cardiovascular deaths at about 5.5 million in 2019, six times the Global Burden of Disease figure for that year. They also estimated that children under five lost 765 million IQ points, and that over 90 percent of both harms fell on low- and middle-income countries.\n\nRemoving lead from products works at population scale. U.S. children aged 1 to 5 had 94.5 percent lower blood lead levels in 2011–2016 than in 1976–1980, a decline the researchers credit largely to federal rules on lead in gasoline, residential paint and plumbing solder. Leaded petrol ended worldwide when Algeria stopped selling it in July 2021, after a UN-hosted campaign that began in 2002.\n\nPaint is next. As of January 2024, 48 percent of countries had legally binding controls on lead paint, according to WHO. Laws and practice can differ. Clark and colleagues (2014) found that paints in Brazil that had averaged 36,000 parts per million of lead tested below detection after a new legal limit, though without public monitoring they couldn’t confirm the law was the main cause. In India, where groups had campaigned against lead paint, 24 of 28 major-brand paints had dropped to 90 parts per million or less.\n\nThe grade is moderate because the links in the chain differ. Strong evidence shows that lead harms and that removing it lowers exposure. Charitology found no rigorous measurement of how much an advocacy campaign causes a law to pass or to be followed.\n\n## Where it sits on the depth scale\n\nThis is **structure** (depth 3). A ban changes the rules of a market so the harm stops being produced, for everyone and without ongoing delivery. Lead already in old paint and soil stays, so the benefit builds over generations.\n\n## Open questions\n\n- How should a funder credit an advocacy group for a law many actors pushed? See [the counterfactual problem](/open-problems/the-counterfactual-problem/) and [measuring the source](/open-problems/measuring-the-source/).\n- One advocacy group’s own preliminary model put its Malawi program at about $14 per DALY-equivalent averted (a DALY is a year of healthy life lost), a figure that more than triples if paint causes less of children’s exposure than assumed. Charitology has not found an independent estimate, so this entry has no Impact Calculator figure.\n- Blood lead is rarely measured in many countries, so it is hard to see what changed." }, { "id": "microcredit", "path": "/record/interventions/microcredit/", "title": "Microcredit", "summary": "Small loans for people with little or no access to banks, usually to start or grow a small business. Randomized evaluations on four continents agree that the average effects are modest rather than transformative.", "depth": 1, "evidence": "strong", "mechanism": "A loan gives a household a sum of money to invest in a business or to manage its spending, to be repaid with interest. The idea is that a lack of capital, more than a lack of skill or effort, holds many poor entrepreneurs back.", "causes": [ "extreme-poverty" ], "timeToEffect": "months", "durability": "years", "feedback": "some", "agency": "co-designed", "conditions": [ "story-bias", "silence-about-failure" ], "sources": [ { "title": "Six Randomized Evaluations of Microcredit: Introduction and Further Steps", "url": "https://www.aeaweb.org/articles?id=10.1257/app.20140287", "publisher": "Banerjee, Karlan and Zinman, American Economic Journal: Applied Economics 7(1)", "year": 2015 }, { "title": "Where Credit Is Due (policy bulletin)", "url": "https://poverty-action.org/publication/where-credit-due", "publisher": "Angelucci, Banerjee, Crépon, Duflo, Glennerster, Karlan, Parienté and Zinman, Innovations for Poverty Action and J-PAL", "year": 2015 }, { "title": "Understanding the Average Impact of Microcredit Expansions: A Bayesian Hierarchical Analysis of Seven Randomized Experiments", "url": "https://www.aeaweb.org/articles?id=10.1257/app.20170299", "publisher": "Rachael Meager, American Economic Journal: Applied Economics 11(1)", "year": 2019 }, { "title": "Can Microfinance Unlock a Poverty Trap for Some Entrepreneurs?", "url": "https://www.nber.org/papers/w26346", "publisher": "Banerjee, Breza, Duflo and Kinnan, NBER Working Paper 26346", "year": 2019, "note": "Working paper, revised in 2024." }, { "title": "Bangladeshi bank wins Nobel prize", "url": "https://www.aljazeera.com/news/2006/10/13/bangladeshi-bank-wins-nobel-prize", "publisher": "Al Jazeera", "year": 2006 } ], "review": "draft", "body": "## What the evidence says\n\nIn 2006 Muhammad Yunus and the Grameen Bank he founded shared the Nobel Peace Prize. The committee praised their efforts to “create economic and social development from below.”\n\nRandomized evaluations then put microcredit to the test. Six were published together in 2015, covering six countries on four continents, cities and villages, and many kinds of lenders and loans. Banerjee, Karlan and Zinman summarized a consistent pattern: modestly positive effects that fell short of transforming borrowers’ lives. A policy bulletin covering seven evaluations reported that:\n\n- Demand was lower than lenders expected. Take-up was 13 to 31 percent in Ethiopia, India, Mexico and Morocco.\n- Six of the seven studies saw some expansion of business activity, but profits rarely rose.\n- None found a significant effect on average household income, and none of the six that measured schooling found children in school more.\n- Six studies found households gained more freedom in how they earned, spent, invested and managed risk.\n- None found widespread harm, even with individual liability or high interest rates.\n\nMeager (2019) pooled seven experiments and concluded that the average effect on business activity and consumption is probably small and may be negligible. Households that already ran a business gained more, but less predictably. In Hyderabad, India, six years after microfinance arrived, households that had run businesses beforehand had about 35 percent more business assets and roughly double the revenue of similar households in control areas, while others showed almost no effect.\n\nThe grade is strong for the finding stated in the summary: several rigorous studies agree that the average effect is modest. That is different from finding that microcredit does nothing, and the debate over what it is worth is in the [Disagreement Register](/record/disagreements/does-microcredit-transform-lives/).\n\n## Where it sits on the depth scale\n\nCharitology places microcredit at **repair** (depth 1), the same level as [cash transfers](/record/interventions/cash-transfers/). It works on a household’s access to money, as a loan rather than a gift, to build income or handle shocks. It doesn’t change the rules that keep people poor. Expanding lending into places that lacked it does change a local financial market, which touches structure, but the evidence suggests the average effect on poverty is modest.\n\n## Open questions\n\n- Are short trials missing the story? In Hyderabad, gains for existing business owners persisted and grew over six years.\n- Can lenders tell in advance which borrowers will gain?\n- How should flexibility and risk management, which don’t show up as income, be valued against other outcomes? See [the exchange rate problem](/open-problems/the-exchange-rate-problem/)." }, { "id": "oral-rehydration-therapy", "path": "/record/interventions/oral-rehydration-therapy/", "title": "Oral rehydration therapy", "summary": "A drink of clean water, salt and sugar that replaces the fluids a child loses to diarrhea, cheap enough to cost a few cents and simple enough to give at home.", "depth": 0, "evidence": "strong", "mechanism": "The solution is absorbed in the small intestine and replaces the water and salts lost in stool. That treats dehydration, historically the main cause of death from diarrhea, usually without a drip or a hospital.", "causes": [ "global-health" ], "timeToEffect": "immediate", "durability": "while funded", "feedback": "some", "agency": "top-down", "conditions": [ "story-bias" ], "sources": [ { "title": "Diarrhoeal disease (fact sheet)", "url": "https://www.who.int/news-room/fact-sheets/detail/diarrhoeal-disease", "publisher": "World Health Organization", "year": 2024 }, { "title": "Oral versus intravenous rehydration for treating dehydration due to gastroenteritis in children (Cochrane systematic review)", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6532593/", "publisher": "Hartling, Bellemare, Wiebe, Russell, Klassen and Craig, Cochrane Database of Systematic Reviews", "year": 2006 }, { "title": "Reduced osmolarity oral rehydration solution for treating dehydration caused by acute diarrhoea in children (Cochrane systematic review)", "url": "https://doi.org/10.1002/14651858.CD002847", "publisher": "Hahn, Kim and Garner, Cochrane Database of Systematic Reviews", "year": 2002 }, { "title": "The effect of oral rehydration solution and recommended home fluids on diarrhoea mortality", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC2845864/", "publisher": "Munos, Fischer Walker and Black, International Journal of Epidemiology 39(Suppl 1)", "year": 2010 }, { "title": "Mapping geographical inequalities in oral rehydration therapy coverage in low-income and middle-income countries, 2000–17", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7388204/", "publisher": "Local Burden of Disease Diarrhoea Collaborators, The Lancet Global Health 8(8)", "year": 2020 } ], "review": "draft", "body": "## What the evidence says\n\nWHO counts diarrheal disease as the third leading cause of death in children aged 1 to 59 months, and puts the toll at about 443,832 children under five each year. Oral rehydration therapy (ORT) replaces lost fluids by mouth, with oral rehydration salts (ORS), which cost a few cents per treatment, or with recommended home fluids.\n\nAs a treatment, ORT is about as good as a drip for most children. A Cochrane review of 17 trials with 1,811 children found no clinically important differences between oral and intravenous rehydration. Oral treatment failed for about 5 percent of children, who then needed a drip, against about 1 percent with intravenous rehydration, and children treated orally left the hospital about a day sooner. A second Cochrane review found that a reduced-osmolarity solution, less concentrated than the older WHO formula, led to fewer unplanned drips, less stool and less vomiting.\n\nThe effect on deaths is estimated rather than measured, because no one can ethically withhold treatment in a trial. Munos and colleagues (2010) estimated that ORS may prevent 93 percent of diarrhea deaths, by projecting a 69 percent reduction seen in three quasi-experimental studies out to full coverage. A 2020 mapping study noted that estimates like this rest on limited evidence, and it tested a much smaller effect in a sensitivity analysis. The strong grade applies to ORT’s core outcome, treating dehydration. The number of lives it saves is less certain.\n\nTwo facts temper the picture. WHO says other causes, such as bacterial infections, likely account for a growing share of diarrhea deaths, which rehydration alone does not treat. And use still lags: in low- and middle-income countries, the share of children with diarrhea who got ORS rose only from 34 percent in 2000 to 44 percent in 2016.\n\n## Where it sits on the depth scale\n\nCharitology places ORT at **relief** (depth 0), not prevention. It treats a child who is already sick, one episode at a time. The diarrhea still happens. WHO lists the measures that prevent it: safe drinking water, improved sanitation, handwashing with soap, exclusive breastfeeding, good hygiene and rotavirus vaccination. Relief at this price and scale is not a lesser category. Because it works at home, ORT can reach children far from any hospital.\n\n## Open questions\n\n- Why does a treatment this cheap reach fewer than half the children who need it? See the history of [how ORT spread](/record/case-studies/oral-rehydration-therapy-spread/) and [the Story Bias](/diagnosis/story-bias/).\n- As the causes of diarrhea deaths shift, how much of ORT’s historical effect still applies?\n- Charitology has not found a reliable published per-dollar estimate of lives saved by ORT alone, so this entry has no Impact Calculator figure." }, { "id": "teaching-at-the-right-level", "path": "/record/interventions/teaching-at-the-right-level/", "title": "Teaching at the Right Level", "summary": "Grouping primary school children by what they can actually read and calculate, rather than by grade, and teaching each group the basic skills it is missing.", "depth": 2, "evidence": "strong", "mechanism": "A simple assessment sorts children by learning level. For a set time each day, or in short intensive camps, they work in groups on the reading and math skills they lack, and teachers use data on what each child can do to guide the groups.", "causes": [ "education" ], "timeToEffect": "months", "durability": "years", "feedback": "strong", "agency": "top-down", "cost": { "outcome": "0.1 standard deviation gain in one student’s broad foundational math score (Zambia’s government-run Catch Up program)", "low": 6.38, "high": 6.38, "asOf": "2022–2024 trial", "source": { "title": "Targeting Foundational Skills to Improve Learning at Scale in Zambia", "url": "https://www.povertyactionlab.org/evaluation/targeting-foundational-skills-improve-learning-scale-zambia", "publisher": "J-PAL" }, "note": "A point estimate from one randomized trial, not an uncertainty interval. The program cost $9.63 per student over two years. Counting only the procedural math skill it targeted gave a different estimate, $2.43 per 0.1 standard deviation, so the choice of test changed apparent cost-effectiveness by a factor of 2.6. The calculator uses the broader measure." }, "conditions": [ "measurement-gap" ], "sources": [ { "title": "Teaching at the Right Level to improve learning (evidence-to-policy case study)", "url": "https://www.povertyactionlab.org/case-study/teaching-right-level-improve-learning", "publisher": "J-PAL", "year": 2019, "note": "Last updated 2022." }, { "title": "Mainstreaming an Effective Intervention: Evidence from Randomized Evaluations of “Teaching at the Right Level” in India", "url": "https://www.nber.org/papers/w22746", "publisher": "Banerjee, Banerji, Berry, Duflo, Kannan, Mukerji, Shotland and Walton, NBER Working Paper 22746", "year": 2016 }, { "title": "From Proof of Concept to Scalable Policies: Challenges and Solutions, with an Application", "url": "https://www.aeaweb.org/articles?id=10.1257/jep.31.4.73", "publisher": "Banerjee, Banerji, Berry, Duflo, Kannan, Mukerji, Shotland and Walton, Journal of Economic Perspectives 31(4)", "year": 2017 }, { "title": "Targeting Foundational Skills to Improve Learning at Scale in Zambia", "url": "https://www.povertyactionlab.org/evaluation/targeting-foundational-skills-improve-learning-scale-zambia", "publisher": "J-PAL" }, { "title": "New education “Smart Buys” report outlines how cost-effectively supporting teachers and parents can lead to significant learning improvements", "url": "https://www.worldbank.org/en/news/press-release/2023/05/09/education-smart-buys-cost-effectively-supporting-teachers-and-parents-can-lead-to-significant-learning-improvements", "publisher": "World Bank", "year": 2023 } ], "review": "draft", "body": "## What the evidence says\n\nTeaching at the Right Level was developed by the Indian nonprofit Pratham and has been tested in randomized evaluations since 2001. J-PAL counts six randomized evaluations in seven Indian states and says the approach has produced some of the largest effects rigorously measured in education. In Uttar Pradesh, short learning camps doubled the number of children who could read a paragraph or story.\n\nThe evaluations also show where it fails. In Bihar and Uttarakhand, government teachers did not adopt the method, even after well-received training. It worked when it had protected time and support. In Haryana, teachers gave it a dedicated hour a day with mentoring from trained government staff, and language scores rose by 0.15 standard deviations. In Uttar Pradesh, intensive 40-day camps run by Pratham volunteers during school hours, plus summer camps, raised language scores by 0.70 standard deviations. J-PAL notes that training alone or materials alone did not improve learning.\n\nAt scale in Zambia the gains are smaller. A randomized trial of the government-run version, Catch Up, in 273 schools found gains of 0.10 standard deviations in literacy and 0.15 in numeracy after two years. Only about a third of students attended a remedial class on a given day, largely because many were absent, had dropped out or had moved schools. Students fully exposed to the program later scored 0.14 standard deviations higher in language and 0.11 in math on grade 7 exams.\n\nIn 2023 the Global Education Evidence Advisory Panel, convened by the World Bank and partners, listed teaching by learning level among its “Great Buys,” its top tier for cost and impact. The grade is strong because many rigorous trials agree that the approach raises basic skills when it is well implemented. How large the effect is depends heavily on delivery.\n\n## Where it sits on the depth scale\n\nCharitology places it at **prevention** (depth 2). It gives children who have fallen behind dedicated time at their own level, so that they don’t leave primary school without basic reading and math. When a ministry runs it through its own teachers, as Zambia does, it moves toward structure. Even then it works alongside the grade-based syllabus rather than replacing it.\n\n## Open questions\n\n- Why are effects so much smaller in Zambia’s government program than in the Indian camps? See [what randomized trials can tell us](/record/disagreements/what-randomized-trials-can-tell-us/).\n- How can governments keep the protected time and mentoring that made the Indian versions work? See [the government question](/open-problems/the-government-question/).\n- Would changing curricula and exams prevent the gap more cheaply than remedial instruction?" }, { "id": "tobacco-taxation-advocacy", "path": "/record/interventions/tobacco-taxation-advocacy/", "title": "Tobacco taxation advocacy", "summary": "Research, coalition-building and public campaigns that help governments raise taxes on tobacco, which makes it more expensive and cuts smoking.", "depth": 3, "evidence": "moderate", "mechanism": "Higher excise taxes raise the price of cigarettes. Higher prices lead some people to quit, fewer young people to start and continuing smokers to smoke less. Advocates supply evidence, coalitions and public pressure to help tax laws pass.", "causes": [ "global-health" ], "timeToEffect": "years", "durability": "years", "feedback": "some", "agency": "top-down", "conditions": [ "symptom-trap", "measurement-gap" ], "sources": [ { "title": "Effectiveness of tax and price policies in tobacco control", "url": "https://doi.org/10.1136/tc.2010.039982", "publisher": "Chaloupka, Straif and Leon for the IARC Working Group, Tobacco Control 20(3)", "year": 2011 }, { "title": "Effectiveness of Tax and Price Policies for Tobacco Control (IARC Handbooks of Cancer Prevention, Volume 14)", "url": "https://publications.iarc.who.int/Book-And-Report-Series/Iarc-Handbooks-Of-Cancer-Prevention/Effectiveness-Of-Tax-And-Price-Policies-For-Tobacco-Control-2011", "publisher": "International Agency for Research on Cancer", "year": 2011 }, { "title": "Tobacco (fact sheet)", "url": "https://www.who.int/news-room/fact-sheets/detail/tobacco", "publisher": "World Health Organization", "year": 2026 }, { "title": "Raising taxes on tobacco", "url": "https://www.who.int/activities/raising-taxes-on-tobacco", "publisher": "World Health Organization" }, { "title": "Sin Tax Reform in the Philippines: Transforming Public Finance, Health, and Governance for More Inclusive Development", "url": "https://documents1.worldbank.org/curated/en/638391468480878595/pdf/106777-PUB-PUBLIC-PUBDATE-7-26-2016.pdf", "publisher": "Kai Kaiser, Caryn Bredenkamp and Roberto Iglesias, World Bank", "year": 2016 } ], "review": "draft", "body": "## What the evidence says\n\nThe effect of the tax is well established. The International Agency for Research on Cancer, part of WHO, convened 25 experts from twelve countries to review the evidence for a 2011 handbook. They found sufficient evidence that higher tobacco taxes and prices reduce overall consumption and the share of people who use tobacco, prevent young people from starting, push current users to quit and lead those who keep using to use less. WHO calls tobacco taxes the single most effective and cost-effective measure for reducing tobacco use.\n\nWHO says tobacco kills more than 7 million people a year, including more than 1.6 million non-smokers exposed to others’ smoke. It recommends that taxes make up at least 75 percent of the retail price, but only 41 countries, covering 12 percent of the world’s population, have reached that level.\n\nAdvocacy is harder to evaluate. The Philippines’ 2012 Sin Tax Reform, which simplified and sharply raised tobacco and alcohol taxes, is a well-documented case. In the first year, excise collections from both rose more than 86 percent, to about $2.44 billion, and the health department’s budget nearly doubled. A World Bank account credits a broad coalition: the finance and health departments, the president, legislators, development partners, and civil society groups including medical professionals and tobacco control advocates. It concludes that no single actor could have brought about the reform alone. When a law has many authors, the share of credit owed to any one advocacy group can’t be measured the way a trial measures a treatment.\n\nThe grade is moderate. Strong evidence shows the tax works, and Charitology found no rigorous test of how much advocacy causes taxes to rise. It has not found a reliable per-dollar estimate of advocacy’s outcomes either, so this entry has no Impact Calculator figure.\n\n## Where it sits on the depth scale\n\nThis is **structure** (depth 3). A tax changes the price of a harmful product for a whole country, so fewer people start and more stop, without anyone being treated one by one. It needs upkeep. The Philippines’ finance secretary warned that the law’s 4 percent yearly increases might not keep pace with rising incomes, which could make cigarettes more affordable over time.\n\n## Open questions\n\n- How should a funder credit advocacy for a law with many authors? See [the counterfactual problem](/open-problems/the-counterfactual-problem/) and [measuring the source](/open-problems/measuring-the-source/).\n- Health effects lag. The World Bank report notes that smoking prevalence is subject to both an effect lag and a measurement lag, so the full impact shows up only in later years.\n- How should it be weighed against direct programs? See [systemic change or proven programs](/record/disagreements/systemic-change-or-proven-programs/)." }, { "id": "vitamin-a-supplementation", "path": "/record/interventions/vitamin-a-supplementation/", "title": "Vitamin A supplementation", "summary": "High-dose vitamin A given every four to six months to children aged 6 to 59 months, in places where vitamin A deficiency is a public health problem.", "depth": 2, "evidence": "moderate", "mechanism": "Vitamin A helps children fight infections. The body stores a large dose and releases it over time, which lowers the risk that infections such as diarrhea kill a child who lacks it. Researchers don’t fully understand which deaths it prevents or how.", "causes": [ "global-health" ], "timeToEffect": "months", "durability": "while funded", "feedback": "weak", "agency": "top-down", "cost": { "outcome": "death averted (GiveWell’s modeled range for its August and September 2024 grants in six countries)", "low": 5200, "high": 17000, "asOf": "April 2025 publication of the August and September 2024 grants", "source": { "title": "Helen Keller International — Vitamin A Supplementation (August & September 2024)", "url": "https://www.givewell.org/research/grants/helen-keller-international-vitamin-a-supplementation-august-september-2024", "publisher": "GiveWell", "year": 2025 }, "note": "These are uncertain models for particular grants and locations, not a measured result or a prediction for a new donation. GiveWell estimates a smaller effect in these settings than the historical trials found. Its earlier February 2024 program model gave a lower range." }, "conditions": [ "measurement-gap" ], "sources": [ { "title": "Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age (Cochrane systematic review)", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC8925277/", "publisher": "Imdad, Mayo-Wilson, Haykal, Regan, Sidhu, Smith and Bhutta, Cochrane Database of Systematic Reviews", "year": 2022 }, { "title": "Vitamin A supplementation every 6 months with retinol in 1 million pre-school children in north India: DEVTA, a cluster-randomised trial", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC3647148/", "publisher": "Awasthi, Peto, Read, Clark, Pande, Bundy and the DEVTA team, The Lancet 381(9876)", "year": 2013 }, { "title": "Vitamin A Supplementation", "url": "https://www.givewell.org/international/technical/programs/vitamin-A", "publisher": "GiveWell", "year": 2024 }, { "title": "Helen Keller International — Vitamin A Supplementation (August & September 2024)", "url": "https://www.givewell.org/node/4250", "publisher": "GiveWell", "year": 2025 }, { "title": "Podcast episode 27: Scrutinizing one of our longest-funded programs", "url": "https://blog.givewell.org/2026/04/02/podcast-episode-27-scrutinizing-one-of-our-longest-funded-programs/", "publisher": "GiveWell", "year": 2026 }, { "title": "Vitamin A supplementation in infants and children 6–59 months of age (eLENA)", "url": "https://www.who.int/tools/elena/interventions/vitamina-children", "publisher": "World Health Organization" } ], "review": "draft", "body": "## What the evidence says\n\nA 2022 Cochrane review pooled 19 trials with about 1.2 million children for its main mortality estimate. Supplementation cut deaths from all causes by 12 percent (risk ratio 0.88) and deaths from diarrhea by a similar share, and the reviewers rated both findings high-certainty. It also reduced night blindness and vitamin A deficiency, and it made vomiting more common in the two days after a dose.\n\nThe trials don’t all agree. The largest by far, DEVTA, followed about 1 million preschool children in north India. It found a 4 percent reduction in deaths that was not statistically significant, far below the 20 to 30 percent its authors had expected from earlier trials. DEVTA pulls the pooled estimate down: without it, the reduction is 23 percent. The Cochrane authors still judge the effect robust.\n\nThe harder question is whether old results hold today. GiveWell, which counts vitamin A among its longest-funded programs, notes that most supporting trials ran 30 to 40 years ago, when infections and deficiency were more common. It now estimates the effect in the places it models at a 1 to 11 percent lower risk of death, and it is exploring whether a new randomized trial is feasible. Charitology grades the evidence moderate for that reason: the historical trial base is strong, but the largest recent trial and today’s changed conditions both point to a smaller effect.\n\n## Where it sits on the depth scale\n\nVitamin A supplementation is **prevention** (depth 2). A dose protects a child for months, then the next round is needed. It corrects the deficiency in each child without changing why the deficiency exists, such as diet and food supply. Work that changes what a whole population eats would sit closer to structure.\n\n## Open questions\n\n- Does supplementation still save lives where deficiency and child deaths have fallen? The Cochrane review found no clear benefit in trials from low-mortality countries, but there were only two, too few to settle it.\n- What explains the gap between DEVTA and the earlier trials? The answer matters for every program built on decades-old evidence. See [the replication rate](/open-problems/the-replication-rate/).\n- The Cochrane authors argue that new placebo-controlled trials would be unethical where deficiency is documented. Funders still need better evidence, which raises the question of what kind of study can fill the gap." }, { "id": "seasonal-malaria-chemoprevention", "path": "/record/interventions/seasonal-malaria-chemoprevention/", "title": "Seasonal malaria chemoprevention", "summary": "Monthly courses of antimalarial medicine given to young children through the peak malaria season, in places where malaria is highly seasonal.", "depth": 2, "evidence": "strong", "mechanism": "Each monthly round gives a child a curative dose of antimalarial medicine, which clears parasites and protects the child for roughly the next four weeks. Repeating it through the high-transmission months covers the period of greatest risk.", "causes": [ "global-health" ], "timeToEffect": "immediate", "durability": "while funded", "feedback": "some", "agency": "top-down", "cost": { "outcome": "death averted (GiveWell’s modeled range for the places where it funds SMC)", "low": 2000, "high": 7000, "asOf": "December 2023 cost-effectiveness analysis", "source": { "title": "Seasonal Malaria Chemoprevention", "url": "https://www.givewell.org/international/technical/programs/seasonal-malaria-chemoprevention", "publisher": "GiveWell", "year": 2024 }, "note": "The range varies by location. It depends on local malaria death rates and on how likely other funders were to pay for the same campaigns. It is a model, not a measured result." }, "conditions": [ "measurement-gap", "fragmentation" ], "sources": [ { "title": "Intermittent preventive treatment for malaria in children living in areas with seasonal transmission (Cochrane systematic review)", "url": "https://doi.org/10.1002/14651858.CD003756.pub4", "publisher": "Meremikwu, Donegan, Sinclair, Esu and Oringanje, Cochrane Database of Systematic Reviews", "year": 2012 }, { "title": "Effectiveness of seasonal malaria chemoprevention at scale in west and central Africa: an observational study", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7718580/", "publisher": "ACCESS-SMC Partnership, The Lancet 396(10265)", "year": 2020 }, { "title": "Seasonal Malaria Chemoprevention", "url": "https://www.givewell.org/international/technical/programs/seasonal-malaria-chemoprevention", "publisher": "GiveWell", "year": 2024 }, { "title": "Updated WHO recommendations for malaria chemoprevention among children and pregnant women", "url": "https://www.who.int/news/item/03-06-2022-Updated-WHO-recommendations-for-malaria-chemoprevention-among-children-and-pregnant-women", "publisher": "World Health Organization", "year": 2022 }, { "title": "Improving implementation of seasonal malaria chemoprevention", "url": "https://tdr.who.int/newsroom/news/item/09-06-2023-improving-implementation-of-seasonal-malaria-chemoprevention", "publisher": "WHO Special Programme for Research and Training in Tropical Diseases (TDR)", "year": 2023 } ], "review": "draft", "body": "## What the evidence says\n\nSeasonal malaria chemoprevention (SMC) is well tested. A 2012 Cochrane review pooled seven trials with 12,589 participants, all in West Africa. Giving young children antimalarial drugs through the transmission season prevented about three quarters of clinical malaria episodes (rate ratio 0.26) and a similar share of severe malaria. The reviewers rated both findings high-quality evidence. The trials were too small to settle the effect on deaths: the estimate pointed to fewer deaths, but its confidence interval included no effect. The most-studied drug pair, amodiaquine plus sulfadoxine-pyrimethamine, made vomiting more common.\n\nDelivery at scale has been measured too. The ACCESS-SMC project gave about 12.5 million monthly treatments in 2015 and 25.1 million in 2016 across seven countries. Case-control studies found 88 percent protection in the 28 days after a treatment. Confirmed outpatient malaria cases fell by between about 25 percent (Nigeria) and 55 percent (The Gambia) in high-transmission periods, and hospital malaria deaths fell by 42 percent in Burkina Faso and 57 percent in The Gambia. Coverage was imperfect: only 53 to 55 percent of eligible children received all four monthly rounds. Four rounds cost about $3.63 per child.\n\nGiveWell describes a large real-world study that found case reductions of about 25 to 55 percent, smaller than in the trials, and it still treats the trial results as the better guide. In 2022 WHO widened its recommendation. SMC is no longer limited to the Sahel or to children under 6, and the number of monthly rounds is no longer capped at four. In 2021, programs reached roughly 45 million children in 15 African countries.\n\n## Where it sits on the depth scale\n\nSMC is **prevention** (depth 2). It stops malaria in the children who receive it, but protection fades within about a month, so campaigns have to return every season. It doesn’t change the conditions that let malaria persist, such as mosquito habitats or weak health systems. In that way it resembles [bed nets](/record/interventions/insecticide-treated-nets/): it saves lives now, and the benefit lasts only as long as the funding.\n\n## Open questions\n\n- What a new dollar achieves depends on whether another funder would have paid for the same campaign. GiveWell puts that chance at 10 to 65 percent, depending on location. That is one form of [the counterfactual problem](/open-problems/the-counterfactual-problem/).\n- ACCESS-SMC found drug-resistance markers at low levels but saw selection for one linked to sulfadoxine-pyrimethamine resistance, which needs monitoring. GiveWell says it has not reviewed resistance data since 2020.\n- Malaria vaccines are being rolled out. GiveWell notes this could make SMC either more or less cost-effective." }, { "id": "vaccination-incentives", "path": "/record/interventions/vaccination-incentives/", "title": "Incentives for childhood vaccination", "summary": "Small cash or in-kind rewards for caregivers who bring a child in for routine vaccinations.", "depth": 2, "evidence": "moderate", "mechanism": "A small reward at each visit gives caregivers an extra reason to bring a child in and to finish the full schedule. The vaccines then protect the child against the diseases themselves.", "causes": [ "global-health" ], "timeToEffect": "months", "durability": "years", "feedback": "some", "agency": "top-down", "cost": { "outcome": "death averted (GiveWell’s modeled range for one incentive program in northern Nigeria)", "low": 1500, "high": 6000, "asOf": "September 2024 update", "source": { "title": "New Incentives", "url": "https://www.givewell.org/charities/new-incentives", "publisher": "GiveWell", "year": 2024 }, "note": "This is GiveWell’s estimate for the program New Incentives runs in specific Nigerian states, and it varies by state. It is not a general figure for vaccination incentives. GiveWell’s main uncertainties are whether vaccines work less well in Nigeria than elsewhere and how much vaccination would have risen anyway." }, "conditions": [ "measurement-gap" ], "sources": [ { "title": "Improving immunisation coverage in rural India: clustered randomised controlled evaluation of immunisation campaigns with and without incentives", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC2871989/", "publisher": "Banerjee, Duflo, Glennerster and Kothari, BMJ 340", "year": 2010, "note": "A 2016 correction fixed the order of the cost figures in the abstract." }, { "title": "New evidence: conditional cash transfers increase immunization coverage in North West Nigeria", "url": "https://www.idinsight.org/article/new-evidence-conditional-cash-transfers-increase-immunization-coverage-in-north-west-nigeria/", "publisher": "IDinsight", "year": 2020 }, { "title": "New Incentives", "url": "https://www.givewell.org/charities/new-incentives", "publisher": "GiveWell", "year": 2024 }, { "title": "Mobile phone-delivered reminders and incentives to improve childhood immunisation coverage and timeliness in Kenya (M-SIMU): a cluster randomised controlled trial", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC5348605/", "publisher": "Gibson and colleagues, The Lancet Global Health 5(4)", "year": 2017 }, { "title": "Interventions for improving coverage of childhood immunisation in low- and middle-income countries (Cochrane systematic review)", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC10698843/", "publisher": "Oyo-Ita and colleagues, Cochrane Database of Systematic Reviews", "year": 2023 } ], "review": "draft", "body": "## What the evidence says\n\nTwo large randomized trials found big gains. In rural Rajasthan, India, where few children were fully immunized, Banerjee and colleagues (2010) compared reliable monthly immunization camps with and without small in-kind incentives, lentils and metal plates. By the end of the study, 39 percent of children in incentive villages were fully immunized, compared with 18 percent where camps ran without incentives and 6 percent in control villages. Each immunization cost about $28 with incentives and $56 without.\n\nIn northwest Nigeria, IDinsight ran a cluster-randomized trial of a program that pays caregivers small cash incentives at vaccination visits. It raised full immunization by 27 percentage points, and coverage of individual vaccines by 14 to 21 points. Coverage also rose by about 20 points in control communities over the same period. GiveWell’s 2024 model assumes a smaller gain of 9 to 18 points, depending on location.\n\nWhere coverage was already high, the effect was smaller. In a Kenyan trial, text-message reminders plus an incentive of 200 shillings raised full immunization by age one from 82 percent to 90 percent.\n\nThe evidence is not uniform. A 2023 Cochrane review, drawing on studies from Mexico, Honduras, Nicaragua and Zimbabwe, rated the evidence on household monetary incentives very low certainty and could not say whether they improve vaccination. Charitology grades the evidence moderate: strong trials show large effects in some settings, the effect varies a great deal with context, and a systematic review of other incentive studies found no clear benefit.\n\n## Where it sits on the depth scale\n\nIncentives are **prevention** (depth 2). The reward raises vaccine uptake, and the vaccines prevent disease in the children who get them. The reward has to keep being paid, and on its own it doesn’t fix supply problems such as unreliable clinics or vaccine stock-outs, though facilities in the Nigerian program reported fewer stock-outs than control facilities. The India trial suggests both sides matter: reliable camps alone tripled full immunization over control villages, and incentives roughly doubled it again.\n\n## Open questions\n\n- How much of the measured rise would have happened anyway? Coverage rose sharply in the Nigerian control areas too. See [the counterfactual problem](/open-problems/the-counterfactual-problem/).\n- Do families keep vaccinating younger children once the payments stop?\n- Do the large effects in India and Nigeria carry over to places where most children are already vaccinated?" } ] }