J-PAL North America Evidence Portal

Education

Based on a review of 96 randomized evaluations by J-PAL staff and affiliated researchers, tutoring—supplemental one-on-one or small group instruction—is an effective method for helping students learn, particularly those who have fallen behind.

• Tutoring programs consistently lead to large improvements in learning outcomes for students, with an overall pooled effect size of 0.37 standard deviations. This impact translates to a student advancing from the 50th percentile to nearly the 66th percentile. 

• Tutoring programs led by teachers or professional (e.g. school staff, education student) tutors are generally more effective than programs that use nonprofessional or parent tutors. Similarly, tutoring programs conducted during school tend to have larger impacts than those conducted after school.

• Tutoring programs that focus on literacy tend to become less effective as students get older. Conversely, tutoring programs that focus on math tend to become more effective as students advance through fifth grade.

• Federal and state policymakers have drawn on J-PAL’s evidence in identifying tutoring as a priority area for investment. In July 2022, the Biden-Harris Administration cited our review when announcing a national effort to increase access to high-quality tutoring. The state government of California drew on this rigorous evidence when it passed Assembly Bill 86, allocating $460 million for hiring paraprofessional tutors as part of the $4.6 billion for expanded learning opportunities to help students catch up.

Based on a J-PAL review of 126 experimental studies, some uses of education technology hold promise in improving learning outcomes in early childhood and K-12 education and boosting college enrollment and success.

• Educational software designed to help students develop particular skills at their own rate of progress have shown enormous promise in improving learning outcomes, particularly in math.

• Technology-based nudges that encourage specific, one-time actions—such as text message reminders to complete college course registrations—can have meaningful, if modest, impacts on a variety of education-related outcomes, often at low costs.

• Combining online and in-person instruction can work as well as traditional in-person only classes, which suggests blended learning may be a cost-effective approach for delivering instruction.

Randomized evaluations have demonstrated the effectiveness of several types of programs, such as simplifying applications, supporting students, and pipeline programs, that can increase college enrollment and graduation rates.

• A J-PAL review of six randomized evaluations showed that simplifying the college application process and supporting students through the transition to college can increase college enrollment and persistence. 

  • Personalized assistance and fee waivers are key elements of effective programs designed to smooth the application process. Providing generic information about college is typically not enough to encourage college enrollment. 

• Results from four randomized evaluations demonstrated that providing community college students with a wide range of comprehensive supports, such as counseling, tutoring, and financial assistance, can improve low rates of persistence and graduation.

• An evaluation of STEM-focused summer programs for high school students found that the programs increased students’ likelihood of attending a highly-ranked university, graduating, and earning a degree in STEM.

See all evaluations in education.

Health

Reducing the cost of health care through an expansion of Medicaid in Oregon caused people to seek more health services and reduced financial strain. 

• Following a lottery in 2008 that gave low-income uninsured adults the chance to apply for Medicaid in Oregon, researchers studied the impact of health insurance in a series of evaluations.

• They found that Medicaid coverage increased health care use, including use of preventive services and visits to emergency departments, reduced depression, and improved self-reported health over the first two years. However, they did not find evidence that Medicaid coverage improved physical health.

• Medicaid coverage also reduced financial strain for individuals; however, they did not find evidence that Medicaid coverage affected employment or earnings.

• In the very short term, expanded Medicaid eligibility for adults increased Medicaid enrollment of their already-eligible children.

Two randomized evaluations in Oregon and Colorado suggest that adopting low-cost, behaviorally-informed mass outreach approaches could substantially increase insurance coverage of vulnerable populations.

• Additional evidence on Medicaid from Oregon demonstrated that improved communication and low-cost “nudges,” such as behaviorally-informed postcards and automated telephone outreach, increased Medicaid enrollment among likely eligible groups by 3.5 percentage points from a base of 38 percent (a 10 percent increase), at a cost of approximately $125 per new enrollee. 

• This increase may be particularly durable among hard-to-reach, low-income populations, and these interventions may be as effective as more resource-intensive, individualized outreach strategies.

• Another study in Colorado evaluated the impact of mailing and emailing information about a complex set of insurance plan options on the state Marketplace website. While consumers who received the information were more likely to shop for plans on the Marketplace website, they were not more likely to switch plans.

An intensive nurse home visiting program for low-income first time mothers in South Carolina had no statistically significant effect on birth outcomes. 

• In the study, nurses conducted home visits that lasted 60–90 minutes per session, occurring every week during the first four weeks after enrollment and then every other week until delivery. Nurses tailored activities to clients’ strengths, risks, and preferences using motivational interviews, educational tools, health assessments, and goal-setting related to prenatal health, child health and development, and future planning. 

• There was no statistically significant effect of receiving nurse home visiting services on the primary composite outcome of adverse birth events, which included preterm birth, low birthweight, small-for-gestational-age birth weight, or perinatal mortality. 

• Evaluation of the overall impact of this intervention is ongoing. Future analyses will consider the effect of the program on birth spacing, early childhood health and development outcomes, and long-term impacts on a range of outcomes including maternal and child health, child school-readiness and performance, maternal educational attainment, and criminal justice involvement.

Providing vision screening and free eyeglasses improved educational outcomes in Florida elementary schools.

• Providing vision screening and free eyeglasses to low-income elementary school children in Florida in 2011 increased achievement on standardized test scores, though providing the screening without the free eyeglasses had no effect.

• The education gains from the intervention faded out within a year and a half for most students, which the researchers suggest may be due, in part, to students losing, breaking, or not continuing to wear their glasses.

Seeing a Black male doctor significantly increased the take-up of preventive health services among black men in Oakland, California.

• In 2017, researchers examined the impact of race concordance (when the race of a patient matches that of the patient’s physician) and incentives on the take-up of preventive health services by Black men.

• For Black men, seeing a Black male doctor significantly boosted demand for all preventive health services, and especially for more invasive tests. For instance, seeing a Black doctor increased take-up of blood pressure measurement among Black men by 11 percentage points, compared to an average take-up rate of 72 percent for patients who were seen by a non-Black doctor (an increase of 15 percent).

In the first year of an ongoing evaluation in the United States, bundled payments–an alternative Medicare payment model–for knee and hip replacements reduced health care utilization without impacting quality of care.

• One of the primary alternative payment models for medical care in the United States is bundled payments, where one payment is made for all services related to a specific episode of care.

• In the first year of an ongoing study across 196 metropolitan statistical areas, bundled payments for knee and hip replacements starting in 2016 reduced health care utilization, with no evidence of harm to health care quality or change in the volume or mix of patients treated.

• Once all payments were factored in, there was no evidence that this bundled payment model had an effect on total Medicare spending, but this may change as hospitals’ incentives change over the course of the study.

Two randomized evaluations of workplace wellness programs in the US found limited impact on employees’ health habits and no impact on their health, employment, or health care costs in the initial years, contrary to previous observational studies. 

• Workplace wellness programs are broadly defined as employer-offered programs to promote health or prevent disease. Although workplace wellness programs vary widely, both studies evaluated comprehensive wellness programs that share common features with most wellness programs in the U.S. today

• A J-PAL review of two randomized evaluations found that although wellness programs improved a small subset of health behaviors—such as self-reported regular exercise and weight management—they had no discernable impact on health, health care spending and utilization, or employment outcomes like absenteeism or productivity.

• One reason that workplace wellness programs did not improve most measured outcomes may be because participants in wellness programs differed systematically from non-participants. This may be because the employees who stood to benefit the most from workplace wellness programs, such as those with poor health habits, were less likely to participate.By better targeting wellness programs, employers could potentially improve participation rates among the types of employees who are most likely to benefit from workplace wellness programs.

Strongly-worded letters sent to high prescribers of antipsychotic drugs caused substantial and long-lasting reductions in prescribing of these drugs with no evidence of negative effects on patients. 

• Antipsychotic drugs such as quetiapine (brand name Seroquel) are frequently prescribed for reasons unsupported by clinical evidence—potentially causing harm and even death.

• In 2015, the Centers for Medicaid and Medicare Services (CMS) sent strongly-worded peer comparison letters to the treatment group stating that their quetiapine prescribing was extremely high relative to their within-state peers and that they were under review by CMS.

• The letters reduced the number of days of quetiapine the PCPs prescribed by 319 days, an 11.1 percent decrease. Two years following the intervention, the results persisted: the effect at this duration was a 15.6 percent decrease.

• This study builds on a 2015 randomized evaluation finding that informative peer comparison letters without the possibility of CMS reviewing the physician’s prescribing activity was insufficient to change prescribing behaviors.

See all evaluations in health.

Crime and Violence Prevention

A J-PAL review of three randomized evaluations found that cognitive behavioral therapy can be an effective approach to reduce criminal behavior among young men.

• Cognitive behavioral therapy (CBT) programs, which aim to empower individuals to evaluate and modify the way they think in order to improve, have reduced engagement in the criminal justice system and improved academic outcomes among Chicago youth.

• When delivered in schools, CBT increased graduation rates by 3 percentage points from a base of 34 percent (a 9 percent increase)

• School delivered CBT reduced arrest rates for violent crime by 3 percentage points from a baseline of 14 percent (a reduction of 20 percent) and reduced total arrest rates by 7 percentage points from a baseline of 60 percent (a 12 percent decrease). The reduction in crime among this group did not persist beyond the year-long program.

• CBT may have been effective because it changed participants’ decision-making processes. In the United States, students in CBT programs learned to slow down their decision-making to better assess situations and choose appropriate responses.

A J-PAL review of thirteen randomized evaluations of summer youth employment programs found that they can consistently reduce involvement in the criminal justice system for participating youth.

• Summer youth employment programs are municipal programs that provide qualifying youth and young adults ages 14 to 24, often from households with low incomes, with a paid, part-time job and related supplemental services during the summer months.

• Researchers observed that summer youth employment programs consistently reduce involvement in the criminal justice system for participating youth for the duration of the program and at least a year beyond. Arrest, arraignment, conviction, and/or incarceration declined across four study sites, with evidence pointing to both contemporaneous and post-program effects.

• In addition, summer jobs programs save lives by reducing deaths from external causes (accidents, homicides, and suicides). As of 2014, the mortality rate for participants in the New York City SYEP between 2005 and 2008 declined by 0.073 percentage points, an 18 percent reduction from a baseline mortality rate of 0.41 percent among all applicants who were not offered a slot in the program. This reduction translates into 83 lives of mostly young men saved because of program participation.

• Because the effects of SYEPs on criminal justice involvement and youth safety last beyond the end of the summer, it is unlikely they are solely a function of youth being kept busy while they are out of school. Rather, researchers hypothesize that longer-term changes are occurring that can act as protective factors, such as development of new socio-emotional skills, contact with new peer networks, and an increase in household income.

 To learn more about the impact of SYEP on employment outcomes, please see the Labor Markets section. 

Simple, low-cost behavioral nudges helped reduce the likelihood that a person with a court summons failed to appear in court in New York City, and consequently reduced pre-trial detention.

• Researchers partnered with policymakers in New York City in 2016 and found that receiving text message reminders that outlined both the consequences of FTA and provided tips for planning how to get to court were able to reduce failures to appear by 10 percentage points from a baseline of 38 percent (a 26 percent decrease), translating to 3,700 fewer arrest warrants per year. 

An intensive reentry and recidivism program in Wisconsin helped formerly incarcerated individuals successfully reintegrate into society.

• Researchers examined whether a program in Wisconsin that provided inmates with services both prior to and after their release could improve their employment prospects and reduce recidivism.

• The services prior to release were offered starting in 2009 and included access to a community employment program, vocational and soft-skills training, remedial education, participation in restorative justice circles, treatment for drug and alcohol abuse, a cognitive therapy program, and meetings with a coordinated care team. After release, services included access to substance-use treatment, participation in the community employment program, and subsidized employment for six months.

• One year later, the program increased employment and reduced the likelihood of re-arrest. Among formerly incarcerated people in the treatment group, 81 percent reported earnings at some point during their first twelve months out of prison, compared to 59 percent of formerly incarcerated people in the control group. 

• However, earnings among people who were formerly incarcerated and employed were low and left many below the poverty line; median annual earnings for formerly incarcerated individuals in the treatment group were US$2,690, compared to US$462 for formerly incarcerated individuals in the control group.

• Since many different services were offered to members of the treatment group, additional investigation is needed to understand which services are most effective and why.

See all evaluations in crime and violence prevention.

Labor Markets

Three randomized evaluations point to considerable discrimination in labor markets in the United States and Canada.

• In a nationwide study intended to quantify hiring discrimination, researchers sent over 80,000 fictional resumes with randomly varying demographic information to large employers in the United States in 2019, 2020, and 2021. The fictional resumes were identical except for certain demographic features: distinctively white and Black names, age, participation in an LGBTQ+ club or group in school, political club participation, gender-neutral vs gender-typical pronouns, and associate degree completion. Resumes with distinctively Black names received lower contact rates than those with distinctively white names, an effect that was especially concentrated among certain firms. There was no overall difference in contact rates based on gender, but some firms discriminated against men and some against women. There was small but significant discrimination against applicants over forty. No other demographic characteristics elicited differences in contact rates.

• In Boston and Chicago, researchers examined the level of racial discrimination in the United States labor market in the early 2000s by randomly assigning identical resumes to have Black-sounding or white-sounding names and observing the impact on requests for interviews from employers. Results found that résumés with white-sounding names received 50 percent more callbacks than those with Black-sounding names, indicating that many employers discriminate against applicants they perceive as being Black.

• In Toronto and Montreal, researchers randomly manipulated thousands of resumes in 2008 to measure the effects that foreign experience and having a name of Chinese, Indian, Pakistani, or Greek origin (all large immigrant groups in Canada) have on callback rates from employers. Changing only the name on a résumé from an English-sounding name to an Indian, Pakistani, or Chinese name decreased the likelihood of a callback by 4.4 percentage points from a base of 15.7 percent (a 28 percent decrease). Résumés with English-sounding names received more callbacks than those with Chinese, Indian, Pakistani, or Greek names. Work experience in Canada increased responses for résumés with non-English-sounding names, but callback rates were still lower than those with English-sounding names.

Four randomized evaluations of nine programs find that sectoral employment training boosts employment and earnings by empowering workers to move into higher-wage jobs.

• Sectoral employment training is a type of job training that equips people to work in high-wage, high-growth occupations such as healthcare, technology, and renewable energy jobs.

• Results from four randomized evaluations, examining nine programs in total, show that sectoral employment programs generate substantial earnings gains for participants in the year following training completion. These earnings persist in the evaluations with longer-term follow-up evidence. 

• Earnings gains from access to sectoral employment programs, among the largest found in evaluations of US training and employment services programs, are driven by increasing the share of participants working in higher-wage jobs.

• The most effective sectoral employment training programs include a combination of upfront screening of applicants, occupational skills training, career readiness training, wraparound support services for participants, and strong connections to employers.

Long-term follow-up studies from two randomized evaluations suggest that childhood factors, including neighborhood quality and early childhood education, impact employment outcomes later in life. 

• The US Department of Housing and Urban Development (HUD) launched the Moving to Opportunity (MTO) project in 1994 to test the impact of offering housing vouchers to families living in neighborhoods with higher poverty rates with the condition that they move to neighborhoods with lower concentrations of poverty. Children whose families moved to neighborhoods with lower poverty when they were young have higher incomes in adulthood. However, moving to a neighborhood with a lower poverty rate had no effect on employment or income for those who were adults when they moved.

• In Tennessee, researchers measured the effect of class size, teacher quality, and classroom quality on earnings and other future outcomes for children participating in the Student/Teacher Achievement Ratio (STAR) project. The study found that more experienced teachers increased future earnings of their students, and that higher quality classrooms also improved future earnings.

An expansion of Earned Income Tax Credit (EITC) eligibility to low-income single adults without dependent children in New York City increased income, employment, tax filing and credit receipt, and payment of child support over a three year period. 

• EITC is one of the largest programs providing support to low-income workers in the United States, but provides little support for workers without dependent children.

• Paycheck Plus tests a more generous tax credit for low-income single adults without dependent children. In New York City, participants in the treatment group were eligible for a Paycheck Plus bonus of up to $2,000 for three years, starting in the 2015 tax season. 

• Results from New York City indicate that Paycheck Plus increased after-bonus income, with effects concentrated among women and the lowest income earners.

• The program also increased employment rates, tax filing and tax credit receipt, and payment of child support. It did not improve self-reported physical health, but it did reduce survey respondents’ risk of depression and anxiety. 

A J-PAL review of thirteen randomized evaluations of summer youth employment programs found that they improve summer labor outcomes and have the potential to improve post-summer labor outcomes. 

• Summer youth employment programs (SYEPs) are municipal programs that provide qualifying youth and young adults ages 14 to 24, often from households with low incomes, with a paid, part-time job and related supplemental services during the summer months.

• SYEPs have consistently been shown to provide employment and additional income to youth who would otherwise have difficulty finding a job during the program summer. 

• SYEPs significantly boost the summer earnings of participants, and surveys suggest that they often use these wages to support their families. Approximately 20 percent of Boston summer job participants reported contributing to paying household bills, and survey participants in Chicago reported almost 80 percent of net wages going to their families or to local businesses. 

• There is little evidence to suggest that SYEPs improve formal sector employment outcomes beyond the summer, but some subsets of youth may experience small benefits compared to the average participant, and adding new components to SYEP may lead to improvements in post-summer labor outcomes.

• In New York City, one study found that providing youth with a letter of recommendation following the summer program improved future employment outcomes. In 2016 and 2017, a subset of participants received a recommendation letter generated from an employer survey about their performance. Youth who received a letter saw a 3.13 percentage point increase in employment the year after participation, a 4.46 percent increase from a baseline of 70.1 percent.  

• There is promising evidence that SYEPs have positive effects on a range of youth development outcomes including socio-emotional skills, academic and career aspirations, and work habits associated with job readiness. 

To learn more about the impact of SYEP on criminal justice outcomes, please see the Crime and Violence Prevention section.

See all evaluations in labor markets.

Housing and Neighborhoods

Moving from public housing in areas with high poverty to neighborhoods with lower poverty improved later-life outcomes for children and reduced the intergenerational persistence of poverty. 

• The US Department of Housing and Urban Development (HUD) launched the Moving to Opportunity (MTO) project in 1994 to test the impact of offering housing vouchers to families living in neighborhoods with high poverty rates with the condition that they move to neighborhoods with lower poverty rates.

• The MTO study found that families that moved to neighborhoods with lower poverty rates were healthier and happier, although moving to a neighborhood with a lower poverty rate had no effect on employment or income for those who were adults when they moved.

• Children who were under 13 when their families moved to neighborhoods with lower poverty rates were more likely to attend college and had substantially higher incomes in adulthood.

• However, moving may be disruptive to children, and children who were 13 or older when their parents moved to areas with lower poverty had slightly lower educational and earnings outcomes relative to children in the control group.

• The long-term results from the MTO study prompted legislative policy action to expand housing choice for low-income families, including providing 53 million dollars in funding toward housing mobility services and expanded housing choice for tens of thousands of low-income families in the United States.

Preliminary results from an ongoing study indicate that a housing mobility program in King County, Washington significantly increased the share of low-income families with children who moved to areas with more opportunities for economic mobility. 

• Motivated by findings from MTO and other studies on the importance of high-upward-mobility neighborhoods to life outcomes, researchers partnered with Seattle Housing Authority (SHA) and King County Housing Authority (KCHA) in Washington to evaluate whether mobility services are effective at encouraging families with children to move to higher-opportunity neighborhoods. This is part of the broader Creating Moves to Opportunity project that aims to better understand how to facilitate moves to neighborhoods with higher opportunity for families with young children. 

• Preliminary results demonstrate that mobility services substantially increased the share of families who chose to move to areas with higher opportunities. Fifty-four percent of families who received mobility services chose to move to areas with higher opportunities, compared to 14 percent of families who received standard services in the control group (a 286 percent increase).

• Qualitative evidence from interviews with a subset of families confirmed that many families would prefer to move to neighborhoods with higher opportunities, but various barriers prevent them from doing so. The interviews suggest that the mobility services were particularly effective due to the program’s ability to customize service according to each family’s specific needs and circumstances.

Providing low-income families with more information about neighborhood and school quality motivates them to move to neighborhoods with higher-rated schools. 

• Researchers added school quality information from GreatSchools to housing listings on AffordableHousing.com, the largest provider of housing listings for Housing Choice Voucher (HCV) recipients, to evaluate the impact on low-income families’ search for housing and their residential locations. 

• Families with school quality information moved to neighborhoods with schools where the share of students scoring proficient or higher on state exams was 1.5 percentage points higher than schools in neighborhoods of families in the control group. 

• For more information, see our Evidence to Policy case study on providing school quality information to improve housing mobility for low-income families. 

Based on a literature review by J-PAL affiliated researchers, many housing programs, such as Housing First, permanent supportive housing, and Housing Choice Vouchers, are effective in reducing homelessness and maintaining housing stability, but there is still much to learn about strategies to reduce and prevent homelessness.

• Rigorous evidence has demonstrated that a Housing First approach—which prioritizes immediate housing without preconditions—can more effectively house people experiencing homelessness than shelter-based approaches. 

• Subsidized long-term housing assistance in the form of Housing Choice Vouchers helps low-income families avoid experiencing homelessness and stay stably- housed.

• Permanent supportive housing increases housing stability for individuals with severe mental illness and for veterans experiencing homelessness. There is limited rigorous evidence on the impact of permanent supportive housing for other groups of people.

• Emergency financial assistance and more comprehensive interventions that provide a range of financial assistance, counseling, and legal support can prevent homelessness among families at risk of losing their homes, but more research is needed on how prevention programs can best be delivered and targeted towards those most in need.

• Legal representation for tenants facing eviction holds promise for improving court-related outcomes for tenants and reducing evictions, although more research is needed on which types of legal tactics and programs are effective.

• Although rapid re-housing is a potentially cost-effective solution to provide immediate access to housing, there is limited rigorous evidence on the impacts of rapid re-housing on long-term housing stability.

See all evaluations on homelessness and housing stability.

Household Finance

Providing payday borrowers in the United States with information about the true costs of payday loans reduced demand for payday loans.

• In 2008 and 2009, researchers provided payday borrowers in the United States information about the true costs of payday loans, in order to find out whether they would respond by changing their demand for the product.

• Better informed individuals significantly reduced both the frequency that consumers took out payday loans and the borrowing amounts, suggesting that getting consumers to think more broadly about the decision to take out a payday loan may result in a reduction in the amount and frequency of payday borrowing.

Repeated notifications with simple, highly relevant information improved US taxpayers’ likelihood of claiming their eligible benefits through the Earned Income Tax Credit (EITC). 

• In partnership with the US Internal Revenue Service (IRS), researchers tested the effectiveness of different messages to taxpayers who were eligible for, but did not claim, the EITC.

• While simple, targeted messages increased take-up of the EITC, information designed to reduce stigma and perceptions of the economic costs of filing paperwork had no effect on benefit claims.

• Based on the results of this study, the IRS revised the notices sent to taxpayers on a national scale.

Higher matching rates for IRA contributions significantly increased IRA participation and contributions among H&R Block clients in St. Louis. 

• In 2005, researchers tested the impact of offering clients different matching rates for contributions to their Individual Retirement Arrangements (IRA).

• They found higher matching rates significantly increased IRA participation and contributions.

• The combination of financial incentives, tax preparer assistance, and the opportunity to use part of an income tax refund to save could generate increases in both the efficacy of federal tax incentives and the willingness of households to contribute to retirement savings accounts.

A study of Supplemental Nutrition Assistance Program (SNAP) eligible households found that informational mailings nearly doubled SNAP enrollment while informational mailings plus application assistance tripled SNAP enrollment. 

• Enrollment in SNAP, previously known as food stamps, is not automatic: individuals must apply and demonstrate their eligibility in order to receive benefits.

• There is substantial variation in take-up rates across eligible populations, and take-up of SNAP benefits is disproportionately low among the elderly. 

• Receiving informational mailings increased SNAP enrollment by 5 percentage points from a baseline of 6 percent in the control group (an 83 percent increase).

• Receiving informational mails plus application assistance increased SNAP enrollment by 12 percentage points (a 200 percent increase relative to the control group).

• Relative to the control group, individuals who enrolled because of the intervention were more likely to be white and to speak English as their primary language.

• Both the lack of information and the time and effort required to complete and submit an application pose barriers to enrollment.

See all evaluations in household finance.

Environment, Energy, & Climate Change 

A J-PAL review of five randomized evaluations and three quasi-experimental evaluations of programs that encourage investments in residential energy efficiency found that they led to relatively small impacts on energy savings and were not cost-effective in reducing greenhouse gas emissions. 

• Residential energy efficiency programs include appliance replacement, retrofits to upgrade inefficient homes, and home audits. Strategies to encourage take-up included information campaigns, discounts, and subsidies for households. 

• Take-up rates for these programs were low (ranging from 1–17 percent), with modest energy savings: Of the four studies that measured impacts on energy use, one found no energy savings and three others found that residential energy efficiency programs achieved only a portion (ranging from 25 percent to 58 percent) of their projected impact. The costs of implementing these programs were greater than the benefits. For example, Installing energy efficiency measures in new homes in Mexico added roughly US$400–500 to construction costs, with no impact on energy use. 

• There is little evidence that a lack of information on energy efficiency decreases take-up. To reduce greenhouse gas emissions, policymakers should consider strategies that come closer to a direct incentive tied to carbon emissions, such as subsidies for energy efficiency that pay per unit of emissions avoided, rather than a flat rate for participation, or informational campaigns. 

Based on a review of randomized evaluations across more than 115 sites in four countries, providing people with social comparisons on their energy or water use, along with tips about how to conserve, consistently reduced consumption by small amounts in many contexts.

• Comparison reports helped people learn about their own resource use, which is otherwise difficult to observe. They also appealed to social norms around conservation, which motivated some people to cut back—often those who consumed the most.

• Across more than 110 utilities in the United States, energy use fell by 1–3 percent over 7–24 months as a result of receiving regular Opower home energy reports. At one utility in Germany, electricity use declined by 0.7 percent over one year. In one site in India, reports reduced electricity use by 7 percent over four months. Water use reports reduced consumption between 3.7–5.6 percent in Costa Rica and the US states of California and Georgia over 2–12 months.

• While effective, home reports alone will not be enough to substantially reduce carbon emissions or address water scarcity. For example, if the entire US population received home energy reports and their effects were lasting and the same at scale, they would achieve about 0.8–1.3 percent of the carbon emissions reductions the United States pledged at the Paris Climate Accord.

See all evaluations in environment and energy.