Table 2.

Fixed and random effect estimates from linear mixed models

	Sample A	Sample B	Sample C
Fixed regression coefficients
Intercept	7.401**	7.234**	7.604**
Age	−0.033**	−0.132**	−0.054**
Cohort	−0.038**	−0.035**	−0.059**
Age×cohort	0.001	0.006**	0.003**
Random variances and covariances
Variance intercept	1.812**	2.474**	1.820**
Variance age	0.010**	0.011**	0.008**
Covariance intercept–age	0.022**	0.057**	−0.007*
Residual variance	1.783**	2.216**	1.957**
Δa−2LL	1,061.2**	316.7**	975.8**

Sample A = respondents born within the years 1924–1939, sample B = respondents born within the years 1909–1924, sample C = respondents born within the years 1909–1939. Asterisks refer to statistical significance (t test for fixed effects, Wald-test for random covariances, χ²-test for Δ_−2LL) with *P < 0.05, **P<0.001

^aDeviance tests, i.e. reduction in −2LL compared with random intercept (compound symmetry) model