Table 2.
Conditional models: Assessing sensitivity to the MAR assumption conditional on covariates
| LCM | SPMM | Parameter Sensitivity | ||||
|---|---|---|---|---|---|---|
|
| ||||||
| Estimate | SE | Estimate | SE | % Change | CSK | |
| Fixed Effects | ||||||
| Intercept | 63.23*** | .82 | 63.56*** | .82 | .52 | −40.24 |
| Slope (Time-Logged) | −6.77*** | .40 | −7.21*** | .39 | 6.50 | 110.00 |
| Covariate Effects on Intercept | ||||||
| Anxiety | 6.81*** | 1.38 | 6.76*** | 1.39 | .73 | 3.62 |
| Mood | 18.01*** | .96 | 17.84*** | .97 | 1.44 | 27.08 |
| Other Disorder | 1.29 | .99 | 1.21 | 1.00 | 6.20 | 8.08 |
| Female | 4.10*** | .63 | 4.06*** | .63 | .98 | 6.35 |
| Age (Centered) | .07 | .09 | .06 | .09 | 14.29 | 11.11 |
| Covariate Effects on Slope | ||||||
| Anxiety | −.47 | .61 | −.55 | .58 | 17.02 | 13.11 |
| Mood | −3.33*** | .45 | −3.49*** | .44 | 4.80 | 35.56 |
| Other Disorder | .82* | .39 | .74 | .39 | 9.76 | 20.51 |
| Female | −.59 | .37 | −.62 | .37 | 5.08 | 8.11 |
| Age (Centered) | .08* | .04 | .08a | .04 | 0 | 0 |
|
| ||||||
| Variance Components | ||||||
| Intercept Variance | 386.55*** | 8.75 | 384.01*** | 8.95 | .66 | 28.38 |
| Slope Variance | 77.82*** | 2.78 | 73.32*** | 2.71 | 5.78 | 166.05 |
| Covariance | −49.69*** | 3.88 | −52.26*** | 3.79 | 5.17 | 67.81 |
*
p<.05;
***
p<.001
Note. Adjustment disorders and males are the referent groups. Residual variances are not tabled. Values range from 73.39 at baseline to 156.57 at the last time point for the LCM. Values range from 74.61 at baseline to 156.41 at the last time point for the SPMM. MAR: Missing at random; CSK: Collins-Schafer-Kam index of model sensitivity; LCM: Latent curve model; SPMM: Shared parameter mixture model.
a
The SPMM-implied point estimate and standard error appears identical to the LCM-implied point estimate and standard error due to rounding error. The latter effect is statistically significant and the former is not.