Table 2.

Class differences in symptom severity at 36 months

	ANOVA			Post hoc Tukey’s tests
				Class 2 vs. class 1		Class 3 vs. class 1		Class 3 vs. class 2
	F	dof	p	t	p	t	p	t	p
ADOS at 36m1
CSS-Tot	1.77	2/232	0.17	–	–	–	–	–	–
CSS-SA	1.04	2/232	0.35	–	–	–	–	–	–
CSS-RRB	2.15	2/232	0.12	–	–	–	–	–	–
ADI-R at 36m2
ADI-Comm3	9.56	2/236	< 0.001*	− 4.25	< 0.001*	− 3.97	< 0.001*	− 0.42	0.91
ADI-Soc3	13.0	2/236	< 0.001*	− 5.04	< 0.00*	− 4.39	< 0.001*	0.01	1.00
ADI-RBI4	5.32	2/236	0.005*	− 2.79	0.015*	− 3.23	0.004*	− 1.28	0.40
SCQ at 36m2
SCQ-Tot3	11.2	2/236	< 0.001*	− 4.40	< 0.001*	− 4.53	< 0.001*	0.50	0.50

This table shows the detailed statistics from the ANOVA-investigated differences between classes in symptom severity at 36 months as measured by the ADOS, ADI-R, and SCQ. When differences were significant, post hoc Tukey’s tests for multiple comparisons were performed for paired comparisons of classes. Differences were considered significant for p < 0.05 (marked as “*”)

ANOVA analysis of variance, Class 1 decreasing adaptive behaviour, Class 2 average/stable adaptive behaviour, Class 3 recovering adaptive behavior, dof degrees of freedom, ADOS Autism Diagnostic Observation Schedule, CSS Calibrated Severity Score, ADI-R Autism Diagnostic Interview-Revised, SCQ Social Communication Questionnaire

¹Data were available for a subsample of n = 235 infants

²Data were available for a subsample of n = 239 infants

³Significant difference per class with p < 0.001

⁴Significant difference per class with p < 0.05