Study evaluation and data analysis
Participants in intervention and control groups were interviewed twice by telephone: at baseline before the study began and again at follow-up after program completion. Interviews lasted 25 to 30 minutes and were conducted by an interviewer not connected with the project. This interviewer obtained verbal informed consent before collecting any study data. Participants received a $10 gift card for each interview completed. Both interviews obtained data for outcome analysis. The baseline interview included questions on personal characteristics; the follow-up interview included questions for process evaluation.
The independent variable was assignment to intervention or control group. Covariates collected included the following demographic characteristics: age, marital status, number of people in the household, years of education, race/ethnicity, and employment status. Self-efficacy for fruit and vegetable consumption was measured using a 5-item scale, ranging from “not at all confident” to “very confident” (21).
Two primary outcomes were measured. Home availability of fruits and vegetables (F&V availability) was measured using a checklist including fruit (14 items) and vegetables (25 items) (22). Items in any form — fresh, frozen, canned, or dried — were counted. Total F&V availability was obtained by summing all items; possible values ranged from 0 to 39. Fruit and vegetable intake (F&V intake) of the study participant was measured using the Centers for Disease Control and Prevention’s Behavioral Risk Factor Surveillance System (BRFSS) (23). Four questions queried the number of times in the past week a respondent had consumed fruit, dark-green vegetables, orange-colored vegetables, or other vegetables. The measure of total F&V intake was constructed by summing times per week for all 4 questions.
Process data from study records included the number of times produce was picked up during the program and the number of classes and events attended (range, 0–5). Process data from intervention participants included their reports of barriers to program participation, disposition of the food received, future willingness to provide partial payment for the program, and overall program assessment. Other process data came from debriefing meetings with agency, farm, and program staff.
Demographic characteristics of the intervention and control groups were compared by using counts and percentages. Differences were assessed by using χ2, Fisher exact, and t tests, as appropriate. General linear models predicting follow-up outcomes were constructed, adjusting for age, education, baseline values of the outcome of interest, and self-efficacy for fruit and vegetable consumption. P values equal to or less than .05 were considered significant, and all calculations were performed using SAS Version 9.2 (SAS Institute, Inc, Cary, NC).