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.