Differential response patterns affect food-security prevalence estimates for households with and without children

To produce national prevalence estimates for "food insecurity" and "food insecurity with hunger," the USDA uses a battery of 18 survey items about symptoms of food-related hardship. Ten items refer to adults in the household, while 8 items refer to children in the household and hence are not asked of households without children. To equate food-security status in households with and without children, the USDA uses a statistical model from item response theory, known as the Rasch model. This model requires an assumption that adult-referenced items have the same severity calibrations for all households, including households with and without children. However, empirical estimates from the 2000 Current Population Survey showed significantly different severity calibrations for households with and without children. These differences have implications for observable response patterns. Holding constant the number of affirmative responses to adult-referenced items, households with children were more likely to respond that they "worried food would run out," and households without children were more likely to be unable to afford "balanced meals." In light of such differences, the Rasch model cannot be used to equate the food-security status of households with and without children. One potential solution would be to estimate household food security by using the same battery of adult-referenced survey items for all households.