Short-term temporal stability in observed retail food characteristics

J Nutr Educ Behav. 2010 Jan-Feb;42(1)L26-32.
Authors: Zenk SN, Grigsby-Toussaint DS, Curry SJ, Berbaum M, Schneider L.

Objective: Use of direct observation to characterize neighborhood retail food environments is increasing, but to date most studies have relied on a single observation. If food availability, prices, and quality vary over short time periods, repeated measures may be needed to portray these food characteristics. This study evaluated short-term (2-week), within-season temporal stability in retail food availability, prices, and quality. Design: In-person observations of retail food stores at 2 time points, 2 weeks apart. Setting: Southwest Chicago, IL. Sample: 157 food stores. Main Outcome Measures: Availability and prices of food items selected from the following food groups: fruit, vegetables, grains, meats and beans, and dairy, as well as fresh produce quality. Analysis: Temporal stability was tested for availability using a McNemar test and for price and quality using a Wilcoxon signed-rank test. Results: Measures of food availability and prices as well as fresh produce quality at stores were generally stable at the 2 time points. Conclusions and Implications: This study suggests that a single observation may be sufficient to accurately characterize within-season food availability, food prices, and fresh produce quality.

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