Does the reference period matter when evaluating the effect of SNAP on food insecurity?

Supplemental Nutrition Assistance Program (SNAP) is the cornerstone food assistance program in the United States and has been shown to reduce the risk of food insecurity. Most research on the causal effect of SNAP on food insecurity relies on the 12-month food insecurity scale along with usage of SNAP at any point during the year. However, recent social surveys ask about experiences with food insecurity in the 30 days prior to the survey. In this paper, we examine whether similar protective effects of SNAP against food insecurity are obtained whether using the 30-day or 12-month food insecurity scale using the December Supplement of the Current Population Survey for 2002–2019. Results indicate comparable average treatment effects of SNAP in mitigating food insecurity across both 30-day and 12-month reference periods.