Table 2.
Results from parallel trends assumption test of all outcome measures during the baseline period of a study assessing two interventions (Healthy Choices and Healthy Nudging) to increase meal participation in three Northeast US urban high schools where all students in all three schools were eligible for free/reduced-price school meals under the US Department of Agriculture Community Eligibility Provision
| Time trends for | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Average number of daily entrées served | 95 % CI | Average number of daily cold entrées served | 95 % CI | Average number of daily hot entrées served | 95 % CI | Average share of entrées served with a vegetable daily | 95 % CI | Average share of entrées served with a fruit daily | 95 % CI | Average share entrées served with a milk daily | 95 % CI | Average number of competitive foods sold daily | 95 % CI | |
| Healthy Nudging School | −0·262*** | −0·404, −0·119 | −0·027 | −0·135, 0·081 | −0·219*** | −0·350, −0·088 | −0·001*** | −0·001, −0·000 | −0·000 | −0·000, 0·000 | −0·000*** | −0·001, −0·000 | −0·406 | −0·588, −0·224 |
| Healthy Choices School | −0·282*** | −0·424, −0·140 | −0·031 | −0·139, 0·077 | −0·235*** | −0·366, −0·104 | −0·001*** | −0·001, −0·000 | −0·000 | −0·000, 0·000 | −0·000*** | −0·001, −0·000 | –† | – |
| Comparison School | −0·286*** | −0·428, −0·144 | −0·032 | −0·140, 0·076 | −0·237*** | −0·368, −0·107 | −0·001*** | −0·001, −0·000 | −0·000 | −0·000, 0·000 | −0·000*** | −0·001, −0·000 | −0·420 | −0·602, −0·239 |
| Number of days | 282 | 282 | 282 | 282 | 282 | 282 | 192 | |||||||
| F statistic | 915·52 | 66·51 | 665·90 | 42·73 | 29·59 | 31·98 | 386·17 | |||||||
| P value | <0·0001 | <0·0001 | <0·0001 | <0·0001 | <0·0001 | <0·0001 | <0·0001 | |||||||
| R 2 | 0·908 | 0·418 | 0·878 | 0·316 | 0·242 | 0·257 | 0·803 | |||||||
Data presented are regression coefficients with 95 % confidence intervals. Regression constant coefficients are omitted from the table, but all were significant at P < 0·05.
Coefficient representing time trend in variable is statistically different from zero: ***P < 0·001.
Competitive foods were removed from the Healthy Choices School, so parallel trends test not conducted on competitive food sales for this school.