Study design for a clinical trial to examine food price elasticity among participants in federal food assistance programs: A laboratory-based grocery store study

Authors: Conrad, Zachary; Jahns, Lisa; Roemmich, James

Submitted to: Contemporary Clinical Trials Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2018
Publication Date: 6/1/2018
Citation: Conrad, Z.S., Jahns, L.A., Roemmich, J.N. 2018. Study design for a clinical trial to examine food price elasticity among participants in federal food assistance programs: A laboratory-based grocery store study. Contemporary Clinical Trials Communications. 10:154-160. https://doi.org/10.1016/j.conctc.2018.05.011.
DOI: https://doi.org/10.1016/j.conctc.2018.05.011

Interpretive Summary: We present a description of an ongoing study that examines how people’s food purchasing decisions are influenced by changes in food prices. We focus primarily on eggs because they are highly nutritious, easy to prepare, can be included in many different dishes, and are a part of a wide range of cultural food menus. The primary aim of this study is to compare egg purchasing behaviors between individuals participating in federal food assistance programs and those not participating in these programs. Our secondary aims are to 1) compare egg purchasing decisions between overweight/obese individuals and non-overweight/obese individuals, 2) examine whether time management decisions influence the effect of income on food purchasing decisions, 3) examine whether social status influences the effect of participation in federal food assistance programs on the purchase of healthy foods, and 4) examine whether stress level influences the effect of social status on the purchase of healthy foods. The results of this study will help increase our understanding of how low-income Americans make food purchasing decisions.

Technical Abstract: We present a protocol for a study investigating the effect of food price changes on purchasing decisions among individuals participating in federal food assistance programs and among those not participating in these programs. We use a laboratory-based grocery store design, which provides greater control over factors influencing food purchasing than in situ experiments in actual grocery stores. We focus primarily, but not exclusively, on eggs because they are highly nutritious, easy to prepare, can be included in many different dishes, and are a part of a wide range of cultural food menus. The primary aim of this study is to compare the own-and cross-price elasticity of eggs between individuals participating in federal food assistance programs and those not participating in these programs. Our secondary aims are to 1) compare the own- and cross-price elasticity of eggs between overweight/obese individuals and non-overweight/obese individuals, 2) examine whether delay discounting moderates the effect of income on own- and cross-price elasticity, 3) examine whether subjective social status moderates the effect of participation in federal food assistance programs on the purchase of high nutrient-dense foods, and 4) examine whether usual psychological stress level moderates the effect of subjective social status on the purchase of high-nutrient dense foods. The results of this study will provide information about the drivers of food demand among low-income adults. A better understanding of these drivers is needed to develop effective nutrition interventions for this large population.