The Supplemental Nutrition Assistance Program (SNAP) is the largest of the federal government’s 15 nutrition assistance programs that operate in the U.S., giving approximately 40 million Americans benefits that can be used to purchase food for at-home consumption.

Following decades of life as the Food Stamp Program, the program was renamed SNAP in 2008 authorizing legislation that states:

…a supplemental nutrition assistance program is herein authorized which will permit low-income households to obtain a more nutritious diet … by increasing food purchasing power for all eligible households who apply for participation.

As empirical microeconomists, we see two interesting hypotheses in that statement. The first is that SNAP will increase food spending by recipient households. The second is that, by doing so, SNAP will change the healthfulness of the foods households buy.

Each of these hypotheses is the subject of a large academic literature. Yet, researchers tackling these questions face considerable methodological challenges. Studying the effect of SNAP requires both high-quality data on household food purchases or diet, and a valid strategy for separating the effect of SNAP from other influences on household spending that may be related to participation in the program.

For example, comparing households on SNAP to those not on SNAP at a single point in time makes it difficult to hold constant the many factors—income, family structure, etc.—that may differ between these two groups. And households responding to a survey may not recall all their food purchases, adding noise to the signal in the data.

To try to circumvent some of these challenges, we have obtained and analyzed large-scale retail data that follows grocery store shoppers over nearly seven years. These data reveal very detailed information on household grocery purchases, and enable us to follow the behavior of the same panel of households over a long period of time, which makes it easier to separate the effect of SNAP from that of other influences.

In a paper forthcoming in the American Economic Review, we find that SNAP is successful in increasing household food expenditure. A household receiving, say, a $200 monthly SNAP benefit can be expected to increase its monthly expenditure on groceries by a bit more than $100. This far exceeds what we would expect for a cash benefit of comparable size, which might increase food spending by only $20 or so.

In ongoing work with Ryan Kessler, we find that these increases in spending do not necessarily translate into large changes in the composition of the household’s diet. The healthfulness of purchased foods does not seem to change very much when households enter or exit the program, even after accounting for the influence of other simultaneous factors.

These findings suggest that SNAP is successful in increasing food expenditures but that this success does not translate into meaningful gains in the nutritional quality of purchased foods. As one of the core tenets of this legislation is to enable households “to obtain a more nutritious diet,” the program may not be achieving its stated aims.

These findings highlight the value of rigorous, data-driven policy evaluation. To us, the findings also suggest a need for further policy experimentation (and rigorous evaluation research) along the lines of the Healthy Incentives Pilot, which used targeted incentives to try to increase SNAP recipients’ purchases of healthful foods. A recent report from the Bipartisan Policy Center includes several interesting suggestions along these lines.

SNAP is one of the federal government’s largest “safety net” programs and is meant to help low-income families increase their food expenditures and access a more healthful diet. How much the program is fulfilling that charge is important to policymakers and, of course, to families working hard to put food on the table.


Photo by Barbara Kalbfleisch/Shutterstock

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