Table 2.
Effects of age, intervention group, time (phase), message engagement, and self-tracking engagement on achieving ≥5% weight loss.
| Equation | Parameter estimate (95% confidence interval) | Standard error | Wald chi-square |
|---|---|---|---|
| Equation 1: messaging | |||
| Age | 0.01 (−2.67, 1.69) | 0.02 | 0.37 |
| Web-only vs web + email intervention | 0.29 (0.02, 0.56) | 0.14 | 4.41∗ |
| Phase | 0.44 (0.12, 0.77) | 0.17 | 7.08∗∗ |
| Low vs high message engagement | −1.37 (−1.99, −0.75) | 0.32 | 18.80∗∗∗ |
| Moderate vs high message engagement | −0.97 (−1.58, −0.37) | 0.31 | 10.00∗ |
| QIC fit estimate: 432.67 | |||
| Equation 2: tracking | |||
| Age | 0.03 (−0.01, 0.06) | 0.02 | 1.55 |
| Web-only vs web + email intervention | 0.25 (−0.02, 0.53) | 0.14 | 3.40 |
| Phase | 0.49 (0.18, 0.80) | 0.16 | 9.76∗∗ |
| Low vs high tracking engagement | −1.12 (−1.68, −0.55) | 0.29 | 15.18∗∗∗ |
| Moderate vs high tracking engagement | −0.42 (−0.94, 0.09) | 0.26 | 2.57 |
| QIC fit estimate: 443.32 | |||
| Equation 3: messaging and tracking | |||
| Age | 0.01 (−0.03, 0.05) | 0.02 | 0.09 |
| Web-only vs web + email intervention | 0.27 (0.01, 0.54) | 0.14 | 3.98∗ |
| Phase | 0.50 (0.19, 0.82) | 0.16 | 9.92∗∗ |
| Low vs high message engagement | −1.32 (−1.98, −0.67) | 0.34 | 15.55∗∗∗ |
| Moderate vs high message engagement | −0.85 (−1.46, −0.24) | 0.31 | 7.35∗∗ |
| Low vs high tracking engagement | −0.50 (−1.11, 0.11) | 0.31 | 2.60 |
| Moderate vs high tracking engagement | −0.08 (−0.64, 0.48) | 0.28 | 0.08 |
| QIC fit estimate: 431.67 |
Note. 180 women used in analyses. QIC = quasi-likelihood under independence model criterion. For phase, phase 1 (baseline to 6 months) = 0 and phase 2 (6 months to 18 months) = 1. ∗ p < 0.05. ∗∗ p < 0.01. ∗∗∗ p < 0.001.