Table 2.
Primary and secondary outcomes
| Outcome | Mean (SD) | Difference to the control condition | ||
|---|---|---|---|---|
| Main modela | Adjusted modelb | |||
| Incentives | ||||
| Cash incentives | % of total step-goal achievement | 61.4 (17.6) | 8.1 [2.1; 14.1] | 8.9 [3.0; 14.8] |
| Total mean steps/day | 7,382 (2,851) | 783 [−135; 1,701] | 887 [−50; 1,832] | |
| Charity incentives | % of total step-goal achievement | 60.2 (19.9) | 6.9 [1.0; 12.8] | 5.0 [−0.9; 10.9] |
| Total mean steps/day | 7,201 (2,824) | 602 [−305; 1,509] | 635 [−154; 1,424] | |
| No incentives | % of total step-goal achievement | 53.3 (16.3) | – | – |
| Total mean steps/day | 6,599 (2,599) | – | – | |
| Planning | ||||
| Action planning | % of weekly goal achievement | 59.3 (26.7) | 1.1 [−2.0; 4.1] | 1.8 [−1.1; 4.7] |
| Weekly mean steps/day | 7,386 (3,194) | 101 [−163; 366] | 148 [−67; 363] | |
| Coping planning | % of weekly goal achievement | 57.9 (25.6) | −0.3 [−3.1; 2.5] | −0.6 [−3.6; 2.3] |
| Weekly mean steps/day | 7,172 (3,066) | −113 [−351; 125] | −44 [−243; 154] | |
| No planning | % of weekly goal achievement | 58.2 (24.9) | – | – |
| Weekly mean steps/day | 7,285 (2,964) | – | – | |
| Self-monitoring prompts | ||||
| Prompt | % of daily goal achievement | 60.5 (48.9) | 1.1 [−1.1; 3.2] | 1.6 [−0.5; 3.6] |
| Steps/day | 7,507 (4,137) | 43 [−114;200] | 32 [−106; 169] | |
| No prompt | % of daily goal achievement | 59.5 (49.1) | – | – |
| Steps/day | 7,464 (4,036) | – | – |
Differences to control conditions correspond to point estimates with 95% confidence intervals in brackets. Boldface indicates statistical significance at α ≤ .05. SD standard deviation.
aModel based on complete cases without adjustment for covariates.
bModel adjusted for missing data and covariates of physical activity (age, gender, baseline step count, smartphone operating system, and employment). Effects for planning interventions and self-monitoring prompts were further adjusted for linear time trends and repeated measures.