TABLE 6.
Analysis of the IMPS study based on six candidate marginal mean regressions and three correlation structures
| Predictors | C(ρ) | Model 1 | Model 2 | Model 3 | Model 4 | Model 5 | Model 6 |
|---|---|---|---|---|---|---|---|
| Time | −1.339 (0.081)* | −1.372 (0.084)* | −1.166 (0.208)* | −1.372 (0.084)* | −1.180 (0.239)* | ||
| Drug | −0.618 (0.182)* | −0.854 (0.236)* | −0.357 (0.438) | −0.860 (0.237)* | −0.524 (0.492) | ||
| Sex | 0.116 (0.184) | −0.188 (0.494) | |||||
| Time × drug | –0.256 (0.271) | −0.252 (0.229) | |||||
| Time × sex | 0.023 (0.171) | ||||||
| Sex × drug | 0.345 (0.460) | ||||||
| JEAIC | AR1 | 27.55 | 398.50 | 16.08 | 17.55 | 17.64 | 22.63 |
| EXC | 94.52 | 491.44 | 90.70 | 91.87 | 94.14 | 101.78 | |
| IND | 223.56 | 496.46 | 209.77 | 210.76 | 209.69 | 212.86 | |
| JEBIC | AR1 | 39.42 | 410.37 | 31.91 | 37.33 | 37.42 | 54.28 |
| EXC | 106.38 | 503.31 | 106.53 | 111.65 | 113.92 | 133.43 | |
| IND | 231.48 | 504.37 | 221.64 | 226.59 | 225.51 | 240.56 | |
| MLIC | AR1 | 261.9 | 321.5 | 255.8 | 256 | 256.5 | 257.5 |
| QICWr | AR1 | 1,554.8 | 1,872.2 | 1,529.6 | 1,529.5 | 1,532.7 | 1,537.1 |
Summary results include WGEE estimates with standard errors in parentheses under an AR1 “working” correlation structure, and JEAIC, JEBIC, MLIC, and QICWr for model selection. It is noted that for MLIC and QICWr, an AR1 correlation structure is selected based on MLICC and QICWr, respectively.
Abbreviations: EXC, exchangeable; IMPS, institute of the mental health schizophrenia; IND, independence; JEAIC, joint empirical Akaike information criterion; JEBIC, joint empirical Bayesian information criterion; MLIC, missing longitudinal information criterion; QICW, weighted quasi-likelihood information criterion; WGEE, weighted generalized estimating equation.
p < 0.05.
The bold values denote the optimal models selected based on different criteria.