WASHINGTON, D.C. — When agronomists evaluate crop yield impact from inputs, such as fertilizer, they compare test plots with a control field. Lack of a control group for the federal SNAP program creates a barrier to evaluating the program’s impact, according to researchers testifying last week to the House Agriculture Subcommittee on Nutrition.

James Sullivan, associate professor of economics at the University of Notre Dame, said people who most need nutrition assistance are already enrolled in SNAP, or the Supplemental Nutrition Assistance Program. That leaves researchers without a “control” for comparing current SNAP recipients.

“If I wanted to test the overall program, I would rewind the clock to 1964, when we were first rolling this out, and roll it out gradually and construct a rigorous design around that rollout,” he said. “But unfortunately, I can’t roll back the clock.”

Many researchers, like Sullivan, advocate for research-backed “evidence-based solutions” for adapting the USDA nutrition program. Evidence-based solutions are based on rigorous social science research and statistical analysis of whether a policy is achieving its initial goals.

Lack of a control group is a challenge for evidence-based assessment of government nutrition programs, because nearly all the nation’s hungry are receiving some nutritional assistance. Even studying those who signed up for SNAP during the recent recession would be difficult to measure, according to Sullivan and others, because there are so many underlying economic factors contributing to increased recipient numbers.

But there are workarounds for evaluating SNAP, said Sullivan, who studies poverty and labor economics as Notre Dame’s director of the Wilson Sheehan Lab for Economic Opportunities. Federal and state governments already have much of the data researchers would need to conduct sound studies, but that information is not always easily obtained.

“One of the most significant barriers to high-quality impact evaluations is limited access to administrative data,” he said.

Data such as changes in household incomes and work participation of households receiving SNAP benefits could be used to evaluate the effectiveness of nutrition programs. Sullivan said a bill introduced in April by Rep. Paul Ryan (R-Wis.) and Sen. Patty Murray (D-Wash.), could help researchers access such data in the future.

“The end result of that is that we have better information. And from better information we have better policy,” he said.

House Republicans say most USDA research about SNAP revolves around topics such as the application process and SNAP recipient gender, age and family composition. “This approach misses the forest through the trees,” said Nutrition Subcommittee Chair Jackie Walorski, a Republican who represents Indiana’s 2nd Congressional District.

“Instead, the Department must move beyond the basics of measuring the ‘number served’ and develop new data points that focus on outcomes like well-being, changes in earnings and family stability.”

But Rep. James McGovern (D-Mass.), the subcommittee’s ranking member, insists the main problem is SNAP is underfunded. “We should look at the body of evidence that shows that the SNAP benefit is too low – that people run out of money to pay for groceries mid-month and have to turn to food pantries to feed them through the end of the month,” said McGovern.

He also questioned why USDA researchers evaluating SNAP were not summoned to testify. Democrats, such as McGovern, are concerned the Republican-led hearings examining SNAP could result in paring back program funding. Meanwhile, some Republicans want to encourage states to innovate how SNAP benefits are delivered and how recipients can move out of broader poverty.

Jeremy Everett, director of the Texas Hunger Initiative at Baylor University, told the committee poverty and hunger are too complex to address separately. His research indicates that local organizations, such as congregations and hunger alleviation groups, are often best-equipped to educate and provide access to nutrition programs.

Everett and his colleagues at Baylor have rigorously evaluated how nutrition benefits are delivered throughout Texas. He said public-private partnerships improving nutrition program delivery, including involvement from faith-based groups, can result in “a foundation for increased social capital for low-income families. And we believe this has the potential to reduce the need for long-term federal assistance.”