Table 2 Comparison of intelligence quotient scores between pre‐injury, T1 and T2, when categorised by severity of injury, time since injury, age, sex and years of education.

		n	IQ scores			ANOVA results		t values
			PI	T1	T2	Wilks' λ	F value	PI−T1	PI−T2	T1−T2
Whole cohort		74	99.79	90.96	92.37	0.606	23.431*	6.023**	5.385**	−0.885
Severity of injury (days)	⩽14	50	98.83	92.79	93.96	0.735	8.663*	−3.543*	3.276*	0.623
	>14	24	101.78	87.14	89.04	0.333	22.040*	−5.998*	4.826*	−0.631
Time since injury (y)	<15	33	99.10	87.30	92.42	0.472	17.343*	−5.974*	3.677*	−2.898
	⩾15	41	100.33	93.91	92.32	0.671	9.571*	−3.122*	3.954*	0.663
Age (y)	<50	45	100.30	88.24	92.27	0.511	20.591*	−6.446**	4.441**	−2.423
	⩾50	29	98.99	95.17	92.52	0.688	6.120*	−1.843	3.015*	0.886
Sex	Male	51	99.04	90.13	92.94	0.641	13.695**	−5.059**	−3.692**	−1.583
	Female	23	101.44	90.72	92.83	0.482	11.266**	−4.374**	−3.990**	−0.900
Education (y)	⩽11	44	95.16	86.99	87.96	0.470	23.704**	−5.319**	−5.680**	−0.560
	>11	30	106.57	95.19	100.17	0.620	8.595**	−4.209**	−2.367	−2.105

*p<0.05. **p<0.01.

ANOVA, analysis of variance; PI, pre‐injury; T1, first assessment after head injury; T2, follow‐up assessment.