Table 3.
Results from simulation to characterize bias. REM = linear random effects model; CLM = conditional linear model with β2 (u) linear; VCM = varying coefficient model with β2(u) unspecified. Each estimate represents a sample average of estimated slopes over 100 replicated datasets, each having 100 subjects with up to 15 repeated measures. Standard errors for simulation-based estimated mean appear in parentheses.
| Estimated slope |
||||
|---|---|---|---|---|
| Underlying modela | True slope (β2) |
REM | CLM | VCM |
| (i) Continuous, smooth | 0.159b | −0.073 (0.018) |
−0.119 (0.035) |
−0.160 (0.028) |
| (ii) Continuous, not smooth | −0.170b | −0.062 (0.015) |
−0.100 (0.027) |
−0.166 (0.033) |
| (iii) Discontinuous | −0.587b | −0.211 (0.018) |
−0.622 (0.031) |
−0.715 (0.038) |
a
See Section 5 for model descriptions.
b
Computed to nearest 0.001 via Monte Carlo simulation.