Measuring elementary-aged children's self-efficacy and proxy efficacy for gardening and related health behaviors

After-school garden programs may be an effective setting to reach school- age children to promote nutritious diets and physical activity, while reducing sedentary behavior. The current analyses drew data from Project PLANTS (i.e., promoting lifelong activity and nutrition through schools), an after-school ran- domized controlled trial focusing on the prevention of obesity among children through garden clubs. The purpose of the current study was to evaluate the psychometric properties of a scale measuring children's self-efficacy and proxy efficacy within the after-school, gardening context. In addition to children's garden self-efficacy, measurement scales for gardening, physical activity, and fruit and vegetable proxy efficacy were also examined. Proxy efficacy was defined as children's confidence that they have the skills and abilities to get their parent to provide behavior-specific opportunities. Participants (N = 969) were fourth grade students (n = 611; age 9.4 years, SD = 0.6; 63% white, 50% female) and fifth grade students (n = 358; age 10.4 years, SD = 0.6; 57% white, 54% female) attending eight elementary schools. Exploratory factor analysis (EFA) (n = 484), confirmatory factor analysis (CFA) (n = 485), multigroup invariance, and tests to examine the sensitivity in detecting expected mean differences determined scale construct and criterion validity. The measurement model included five constructs: garden self- efficacy (seven items), garden barrier self-efficacy (four items), parent-directed proxy efficacy for physical activity opportunities (six items), fruit and vegetable availability (seven items), and opportunities to garden (four items). The five-factor model fit the data well [comparative fit index (CFI) = 0.958], demonstrating factor determinacy coefficients ≥ 0.940. Tests of invariance (equal form, factor loadings, and indicator intercepts) were acceptable between genders [change in CFI (∆CFI) = 0.000], fourth and fifth graders (∆CFI = 0.000), and normal and overweight/obese weight status children (∆CFI = 0.000). Females had greater garden self-efficacy, garden barrier self-efficacy, garden proxy efficacy, and fruit and vegetable proxy efficacy. The current measurement model demonstrated good factorial validity, confirming the unbiased generalizability across gender, grade level, and body mass index subgroups. Further validation is suggested in additional populations and across time points.