. 2015 Jun 21;6:40. doi: 10.1186/s13229-015-0032-1

Table 4.

Q-CHAT item descriptives at 18 (n = 368) and 24 months (n = 396) and test-retest reliability and differences between mean item scores at 18 and 24 months (n = 294)

	18 M	24 M	p***	Difference	Effect size of difference
	Mean (SD)	Mean (SD)	p***	z	r
1. Looks when name called	0.50 (0.7)	0.49 (0.7)	.49	−.37^b	.02
2. Eye contact	0.62 (0.7)	0.56 (0.7)	.46	−1.43^b	.08
3. Lines objects up^a	1.72 (1.0)	2.13 (1.0)	.38	−5.57***^c	.38
4. Understand child’s speech	2.07 (1.1)	1.59 (0.9)	.45	−5.88***^b	.34
5. Protoimperative pointing	0.32 (0.7)	0.52 (0.8)	.27	−3.92***^c	.23
6. Protodeclarative pointing	0.61 (0.9)	0.67 (0.9)	.40	−1.08^c	.06
7. Interest maintained by spinning object^a	1.26 (1.0)	1.26 (1.0)	.42	−.30^b	.02
8. Number of words^a	2.71 (0.8)	2.01 (1.0)	.57	−10.69***^b	.62
9. Pretend play	0.91 (1.0)	1.4 (1.2)	.37	−6.59***^c	.38
10. Follows a look	0.86 (0.9)	0.99 (0.9)	.43	−2.66**^c	.15
11. Sniffs/licks unusual objects^a	2.03 (1.3)	1.38 (1.2)	.32	−7.19***^b	.42
12. Uses hand as tool^a	3.02 (1.2)	2.8 (1.2)	.28	−2.11*^b	.12
13. Walks on tiptoes^a	1.48 (1.2)	1.36 (1.0)	.51	−1.36^b	.08
14. Adapts to changes in routine	0.95 (0.6)	1.01 (0.7)	.19	−1.64^c	.10
15. Offers comfort	1.56 (1.2)	1.46 (1.1)	.57	−2.29*^b	.13
16. Does same thing over and over again^a	2.93 (1.1)	2.32 (1.3)	.44	−7.21***^b	.42
17. Typicality of first words	0.99 (1.1)	0.72 (0.8)	.27	−3.76***^b	.22
18. Echolalia^a	2.67 (1.2)	2.96 (1.2)	.38	−4.24***^c	.25
19. Gestures	0.31 (0.6)	0.39 (0.7)	.36	−1.33^c	.08
20. Unusual finger movements^a	1.49 (1.4)	1.19 (1.3)	.47	−3.30**^b	.19
21. Checks reaction	1.24 (1.0)	1.34 (1.0)	.37	−1.45^c	.08
22. Maintenance of interest^a	1.16 (1.0)	1.33 (1.0)	.42	−1.91^c	.11
23. Twiddles objects repetitively^a	2.14 (1.2)	1.54 (1.2)	.39	−7.59***^b	.44
24. Oversensitive to noise^a	1.44 (1.1)	1.29 (1.0)	.33	−1.66^b	.10
25. Stares at nothing with no purpose^a	0.59 (0.9)	0.49 (0.84)	.35	−1.17^b	.07

*p < .05, **p < .01, ***p < .001 (all ρ correlations have p < .001 in this table)

^aReverse-scored items

^bWilcoxon signed-rank test z-scores based on positive ranks

^c z-scores based on negative ranks