Table 6.
Estimated associations between baseline predictor and change in health from inappropriate use of change score analyses (i.e. in situations where RTM was assumed to occur)
| Dependency (b drop) | b pred (SE) | Coverage of 95% C.I. | Diff | ||
|---|---|---|---|---|---|
| Pred. | V1 | V2 | |||
| 0 | 0 | 0 | -.02 (.04) | 57% | 0.00 |
| .3 | .3 | 0 | -.05 (.05) | 84% | 0.12 |
| .3 | .3 | .1 | -.04 (.05) | 77% | 0.08 |
| .3 | .3 | .3 | -.02 (.05) | 62% | 0.00 |
Dependency is the magnitude (bdrop) of the regression of liability of dropping out on each of the three study variables. Pred = baseline predictor. V1 = the main variable at baseline (baseline health), V2 = the main variable at follow-up (follow-up health). SE = standard error. bpred = regression coefficient from predictor to change in health. Coverage of 95% C.I. = the percentage of the 500 samples with an estimated bpred with a 95% confidence interval containing the true population value. Diff = estimated change score (follow-up health minus baseline health). bpred, SE, and Diff are average results over the 500 generated samples. N in the original samples was 1000. Attrition rate was 50%. The first line shows results when attrition was completely random.
The true population value was bpred = - .10.