Inter-rater reliability of a food store checklist to assess availability of healthier alternatives to the energy-dense snacks and beverages commonly consumed by children

Background: Food stores have gained attention as potential intervention targets for improving children's eating habits. There is a need for valid and reliable instruments to evaluate changes in food store snack and beverage availability secondary to intervention. The aim of this study was to develop a valid, reliable, and resource-efficient instrument to evaluate the healthfulness of food store environments faced by children. Methods: The SNACZ food store checklist was developed to assess availability of healthier alternatives to the energy-dense snacks and beverages commonly consumed by children. After pretesting, two trained observers independently assessed the availability of 48 snack and beverage items in 50 food stores located near elementary and middle schools in Portland, Oregon, over a 2-week period in summer 2012. Inter-rater reliability was calculated using the kappa statistic. Results: Overall, the instrument had mostly high inter-rater reliability. Seventy-three percent of items assessed had almost perfect or substantial reliability. Two items had moderate reliability (0.41-0.60), and no items had a reliability score less than 0.41. Eleven items occurred too infrequently to generate a kappa score. Conclusion: The SNACZ food store checklist is a first-step toward developing a valid and reliable tool to evaluate the healthfulness of food store environments faced by children. The tool can be used to compare availability of healthier snack and beverage alternatives across communities and measure change secondary to intervention. As a wider variety of healthier snack and beverage alternatives become available in food stores, the checklist should be updated.