Table 4. Reliability and concurrent validity of the teacher SDQ at different ages.

	Complete		4–5 years		6–7 years		8–10 years
	n = 387	n = 342	n = 122	n = 107	n = 124	n = 110	n = 141	n = 125
SDQ-T subscales	Cronbach α	Correlation coefficient	Cronbach α	Correlation coefficient	Cronbach α	Correlation coefficient	Cronbach α	Correlation coefficient
Emotional Symptoms	0.73	0.54	0.62	0.64	0.80	0.53	0.75	0.46
Conduct Problems	0.64	0.57	0.70	0.69	0.44	0.54	0.64	0.51
Hyperactivity / Inattention	0.86	0.67	0.88	0.72	0.86	0.65	0.84	0.64
Peer Problems	0.60	0.46	0.52	0.36	0.64	0.52	0.65	0.51
Prosocial Behavior	0.81	-0.43	0.84	-0.57	0.82	-0.34	0.75	-0.38
Total Difficulties Score	0.80	0.73	0.83	0.82	0.77	0.75	0.79	0.63

All correlations were significant at the 0.01 level (Spearman’s correlation coefficient). The emotional subscale of the SDQ-T was correlated with the Internalizing broadband scale of the TRF. The conduct problem scale of the SDQ-T was correlated with the Externalizing broadband scale of the TRF. The hyperactivity / inattention subscale of the SDQ-T was correlated with the Attention Problem scale of the TRF. The peer problem subscale of the SDQ-T was expected to have the highest correlation with the Social Problem scale of the TRF. The SDQ-T prosocial subscale, which includes questions about strengths, was thought to have a strong negative correlation with the Total Problems scale of the TRF.