Table 4. Panel A. Regressions Predicting the Change in Participants’ Weekly Workouts from the Four-Week Intervention Period to Post-Intervention Weeks 1–4.
This table reports a series of ordinary least squares regressions predicting a study participant’s change from the four-week intervention period to the four weeks following the intervention period in average weekly number of (a) overall workouts, (b) workouts initiated during their workout window, and (c) workouts initiated outside of their workout window. In each column, we report the mean change for the control group. The primary predictors included in these regressions are treatment status indicators, which indicate the size of the incentive offered for exercise ($3 versus $7) and the flexibility of the workout schedule (flexible versus routine). We report pairwise Wald tests to assess whether or not all paired regression coefficients reported differ significantly from each other.
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | |
|---|---|---|---|---|---|---|---|---|---|
| Change in Total Workouts | Change in Total In-Window Workouts | Change in Total Out-of-Window Workouts | Change in Total Workouts | Change in Total In-Window Workouts | Change in Total Out-of-Window Workouts | Change in Total Workouts | Change in Total In-Window Workouts | Change in Total Out-of-Window Workouts | |
| Flexible Payment $3 | −0.37*** (0.10) | −0.25*** (0.07) | −0.13 (0.08) | ||||||
| Flexible Payment $7 | −0.61*** (0.10) | −0.34*** (0.07) | −0.31*** (0.08) | ||||||
| Routine Payment $3 | −0.28** (0.10) | −0.51*** (0.07) | 0.19* (0.08) | ||||||
| Routine Payment $7 | −0.51*** (0.10) | −0.81*** (0.08) | 0.22** (0.08) | ||||||
| $3 Interventions | −0.33*** (0.09) | −0.38*** (0.06) | 0.03 (0.08) | ||||||
| $7 Interventions | −0.56*** (0.09) | −0.57*** (0.07) | −0.05 (0.08) | ||||||
| Flexible Interventions | −0.49*** (0.09) | −0.29*** (0.06) | −0.22** (0.08) | ||||||
| Routine Interventions | −0.40*** (0.09) | −0.66*** (0.07) | 0.20** (0.08) | ||||||
|
| |||||||||
| Mean Values of Control Group | −0.35 | −0.17 | −0.21 | −0.35 | −0.17 | −0.21 | −0.35 | −0.17 | −0.21 |
| Observations | 2508 | 2508 | 2508 | 2508 | 2508 | 2508 | 2508 | 2508 | 2508 |
| R-squared | 0.03 | 0.07 | 0.08 | 0.03 | 0.04 | 0.01 | 0.02 | 0.06 | 0.08 |
|
| |||||||||
| Wald Test ($3 Flexible-$7 Flexible) | |||||||||
| Difference in Coefficients | 0.24*** (0.07) | 0.09+ (0.05) | 0.18*** (0.05) | ||||||
| Wald Test ($3 Flexible-$3 Routine) | |||||||||
| Difference in Coefficients | −0.09 (0.06) | 0.26*** (0.06) | −0.32*** (0.04) | ||||||
| Wald Test ($3 Flexible-$7 Routine) | |||||||||
| Difference in Coefficients | 0.14* (0.07) | 0.56*** (0.06) | −0.35*** (0.05) | ||||||
| Wald Test ($7 Flexible-$3 Routine) | |||||||||
| Difference in Coefficients | −0.33*** (0.07) | 0.17** (0.06) | −0.50*** (0.05) | ||||||
| Wald Test ($7 Flexible-$7 Routine) | |||||||||
| Difference in Coefficients | −0.10 (0.07) | 0.47*** (0.07) | −0.53*** (0.05) | ||||||
| Wald Test ($3 Routine-$7 Routine) | |||||||||
| Difference in Coefficients | 0.23*** (0.07) | 0.30*** (0.07) | −0.03 (0.04) | ||||||
| Wald Test ($3-$7) | |||||||||
| Difference in Coefficients | 0.24*** (0.05) | 0.20*** (0.04) | 0.07* (0.03) | ||||||
| Wald Test (Flexible-Routine) | |||||||||
| Difference in Coefficients | −0.10* (0.05) | 0.36*** (0.04) | −0.42*** (0.03) | ||||||
Note: Standard errors clustered by workout buddy pair are in parentheses.
p<0.10
p<0.05
p<0.01
p<0.001.
The control variables in the regressions are indicators for randomization strata (12 strata: three randomization dates, crossed with whether or not workout window perfectly overlapped with partner’s workout window, crossed with whether or not self-reported pair number of workouts per week was above median for randomization date), as well as an indicator for missing workout window.