Figure 8.

Top row, left to right: Observed residuals ${\widehat{\epsilon }}_{ij}\left(t\right)$ for model (8); empirical covariance for ${\widehat{\epsilon }}_{ij}\left(t\right)$ for model (8); empirical covariance for ${\widehat{\epsilon }}_{ij}\left(t\right)$ for model (9) with FPC-based random intercepts; empirical covariance for ${\widehat{\epsilon }}_{ij}\left(t\right)$ for model (9) with spline-based random intercepts; legend for covariance values. Bottom row: Empirical correlations.