Table 4.

Estimated means and variances of IRT-based Neuroticism and Extraversion latent scores based on EPQ-R item data, after taking into account measurement non-invariance across cohorts

	Neuroticism		Extraversion
Cohort	Mean (SE)	Variance	Mean (SE)	Variance
9. Korcula	−0.55 (0.06)	2.28	1.41 (0.07)	2.10
13. NBS	−1.33 (0.07)	2.94	0.60 (0.07)	3.52
16. ORCADES	−1.47 (0.08)	2.56	0.36 (0.08)	3.10
19. QIMR adults	−0.72 (0.06)	2.35	0.76 (0.07)	4.12
22. VIS	−0.33 (0.06)	2.22	1.10 (0.06)	2.02
Overall average	−0.83 (0.23)	0.30a	0.82 (0.21)	0.23a

^aBetween cohort variance