Table 3.
Adjusted Differences in Proportion of Participant-Days Achieving the 7000-Step Goal*
| Group Comparison, by Model | Intervention (wk 1–13) | Follow-up (wk 14–26) | ||
|---|---|---|---|---|
|
|
|
|||
| Difference in Proportion of Participant-Days Achieving the Goal (95% CI) | P Value | Difference in Proportion of Participant-Days Achieving the Goal (95% CI) | P Value | |
| Main model† | ||||
|
| ||||
| Gain incentive vs. control | 0.06 (−0.04 to 0.15) | 0.25 | 0.01 (−0.08 to 0.10) | 0.85 |
|
| ||||
| Lottery incentive vs. control | 0.06 (−0.03 to 0.15) | 0.156 | −0.01 (−0.09 to 0.06) | 0.78 |
|
| ||||
| Loss incentive vs. control | 0.16 (0.06 to 0.26) | 0.001 | 0.07 (−0.02 to 0.14) | 0.110 |
|
| ||||
| Main model adjusted by device‡ | ||||
| Gain incentive vs. control | 0.06 (−0.04 to 0.15) | 0.23 | 0.01 (−0.08 to 0.09) | 0.87 |
|
| ||||
| Lottery incentive vs. control | 0.07 (−0.02 to 0.15) | 0.151 | −0.01 (−0.09 to 0.06) | 0.77 |
|
| ||||
| Loss incentive vs. control | 0.16 (0.06 to 0.26) | 0.001 | 0.07 (−0.01 to 0.14) | 0.106 |
| Main model adjusted by device‡ and with missing data coded as not meeting goal | ||||
|
| ||||
| Gain incentive vs. control | 0.06 (−0.03 to 0.15) | 0.21 | −0.01 (−0.09 to 0.06) | 0.71 |
|
| ||||
| Lottery incentive vs. control | 0.06 (−0.03 to 0.15) | 0.22 | −0.02 (−0.09 to 0.06) | 0.62 |
|
| ||||
| Loss incentive vs. control | 0.14 (0.05 to 0.24) | 0.004 | 0.06 (−0.02 to 0.13) | 0.120 |
*
Boldface values meet the significance threshold of P < 0.017.
†
Adjusted for repeated measures of daily participant step counts and for temporal trends by week using all collected data. For each day, each participant had a binary outcome measure (0 or 1) based on whether he or she achieved the 7000-step goal. Difference in proportions was estimated for each group relative to the control group. CIs and P values were obtained using the bootstrapping procedure.
‡
Type of smartphone.