Table 2.
Weekly spending ($) among 354 shoppers participating in a randomized controlled trial of a double value incentive on fruits and vegetables in a Maine supermarket. Values are mean (SE) unless indicated otherwise.
| Intervention | Intervention/Redeemed Incentives | Control | Difference-in-Difference (Intervention vs. Control) Mean (95% CI) | % change | P-value | Difference-in-Difference (Intervention: Redeemed Incentives vs. Control) Mean (95% CI) | % change | P-value | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Baseline | Intervention | Baseline | Intervention | Baseline | Intervention | |||||||
| Total fruits and vegetables | 11.85 (1.11) | 13.65 (1.08) | 14.90 (1.38) | 19.09 (1.34) | 13.06 (1.15) | 13.03 (1.11) | 1.83 (0.29, 3.88) | 15.4 | 0.02 | 4.23 (2.39, 6.06) | 28.4 | <0.001 |
| Fruits | 6.53 (0.69) | 7.12 (0.67) | 8.05 (0.87) | 9.91 (0.85) | 7.26 (0.71) | 7.08 (0.69) | 0.77 (-0.19, 1.73) | 11.8 | 0.11 | 2.04 (0.90, 3.17) | 25.3 | <0.001 |
| Vegetables | 5.32 (0.50) | 6.53 (0.48) | 6.85 (0.62) | 9.19 (0.59) | 5.80 (0.52) | 5.95 (0.49) | 1.06 (0.23, 1.89) | 19.9 | 0.01 | 2.19 (1.20, 3.18) | 32.0 | <0.0001 |
| Fresh fruits and vegetables | 10.93 (1.05) | 12.81 (1.02) | 13.74 (1.31) | 17.91 (1.26) | 12.18 (1.08) | 12.09 (1.05) | 1.97 (0.49, 3.44) | 18.0 | <0.01 | 4.25 (2.51, 6.00) | 30.9 | <0.0001 |
| Frozen fruits and vegetables | 0.56 (0.07) | 0.48 (0.07) | 0.68 (0.09) | 0.66 (0.09) | 0.48 (0.07) | 0.59 (0.07) | −0.18 (−0.33, −0.04) | −32.1 | 0.01 | −0.12 (−0.29, 0.06) | −17.6 | 0.19 |
| Canned fruits and vegetables | 0.36 (0.05) | 0.36 (0.05) | 0.48 (0.07) | 0.52 (0.06) | 0.40 (0.05) | 0.35 (0.05) | 0.05 (-0.05, 0.15) | 13.9 | 0.34 | 0.09 (-0.04, 0.21) | 18.8 | 0.16 |
Values reflect spending before transaction-level discounts were applied. Holiday weeks of Thanksgiving (11/22–11/28) and Christmas (12/20–12/26) were excluded. “Intervention/redeemed-incentives” is defined as those shoppers assigned to incentives who made a transaction during the intervention period in which the 50% incentive was redeemed at least once (n=123). Statistical tests are two-tailed t-tests from regressions with random intercepts to account for clustering of observations within individuals. All models are unadjusted for demographics.