Studies of food security in the U.S. can be divided into two broad groups. The first group uses the USDA's Food Security Survey Module, a validated survey instrument for assessing household food security. Available in a full 18-item form or an abbreviated 6-item "short form," this instrument asks about a household's experiences with food insufficiency and how they responded to a lack of food during the twelve months preceding the survey.

The second group takes what we call the "red flag approach." Here, respondents typically are asked from one to three questions about their household's food circumstances, usually as part of a larger focus on the overall economic well-being of the household. Examples of these questions include: Has there ever been a time when you were unable to buy food? Were there instances when someone in your household skipped at least one meal because they did not have enough money to buy food? Was there ever a time when an adult or child in your household went hungry? Affirmative answers to these questions can be interpreted as "red flags," suggesting the possible presence of food insecurity or even hunger.