Submitted to: Journal of Nutrition Education and Behavior
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/1/2006
Publication Date: 12/1/2006
Citation: Baranowski, T., Missaghian, M., Broadfoot, A., Watson, K., Cullen, K., Nicklas, T., Fisher, J., Baranowski, J., O'Donnell, S. 2006. Fruit and vegetable shopping practices and social support scales: A validation. Journal of Nutrition Education and Behavior. 38:340-351. Interpretive Summary: Children who have more fruit and vegetables at home tend to eat more fruit and vegetables. The practices that shoppers use when food shopping, and whether their spouse or others at home socially support the fruit and vegetable purchases, could influence whether fruit and vegetables are purchased and thereby home fruit and vegetable availability. Scales were created for fruit and vegetable shopping practices and social support for fruit and vegetable purchases. Traditional and the latest (Item Response Modeling) procedures were employed to test the psychometric characteristics of each scale. Adequate levels of validity and reliability were obtained with 166 food shoppers (with children at home) for each scale, although each could be improved by better measuring the extreme ends of the underlying distribution. The scales are now available for use in research to understand influences on home fruit and vegetable availability.
Technical Abstract: OBJECTIVE: To assess the psychometric characteristics of new scales of shopping practices and social support for purchasing fruits and vegetables. DESIGN: Participants were recruited in front of diverse grocery stores. Telephone data collection was done on 2 occasions, separated by 6 weeks. PARTICIPANTS: 166 food shoppers with children at home participated. MAIN OUTCOME MEASURES: New scales of food shopping practices and social support for purchasing fruits and vegetables were psychometrically analyzed and related to a measure of home fruit or vegetable availability as a test of construct validity. ANALYSIS: Both classical test and item response theory procedures were used. Correlations related the new measures to home fruit and vegetable availability. RESULTS: Single dimension scales were specified for fruit and vegetable shopping practices (35% of the variance), fruit purchase social support (53% of the variance), and vegetable purchase social support (52% of the variance). Item response theory difficulty estimates varied from -0.64 to 0.73 for fruit and vegetable shopping practices, from -0.55 to 0.33 for fruit purchase social support, and from -0.55 to 0.34 for vegetable social support. Each scale significantly correlated with home fruit and vegetable availability (construct validity), even after controlling for social desirability of response (0.19 for shopping practices, 0.37 for fruit purchasing social support, and 0.28 for vegetable purchasing social support). Person separation reliability was 0.80 for food shopping practices, 0.74 for fruit purchasing social support, and 0.73 for vegetable purchasing social support. CONCLUSION: The scales performed well. IMPLICATIONS FOR RESEARCH AND PRACTICE: These scales are now available to help better understand fruit and vegetable shopping practices, fruit purchase social support, and vegetable purchase social support.