Table 2 Total and Factor Q-CHAT raw scores at 18 and 24Â months
|  | 18 months (n = 368) | 24 months (n = 396) | Statistics | |||
|---|---|---|---|---|---|---|
| Â | M (SD) | Range | M (SD) | Range | Difference between Q-CHAT scores at 18 and 24Â months | Relationship between Q-CHAT scores at 18 and 24Â months (r) |
Q-CHAT 25 (total) | 35.57 (7.21) | 12–59 | 33.20 (7.70) | 9–59 | t(293) = 6.01, p < .0001, d = .32 | .64*** |
Q-CHAT social-communicative ALTs (factor 1; 10 items) | 9.94 (4.18) | 2–27 | 10.62 (4.51) | 2–33 | t(293) = −3.17, p = .002, d = .16 | .64*** |
Q-CHAT non-social/behavioral ALTs (factor 2; 8 items) | 13.05 (5.11) | 0–31 | 10.80 (5.14) | 0–26 | t(293) = 8.62, p < .0001, d = .45 | .60*** |
Q-CHAT speech/language (factor 3; 4 items) | 8.43 (2.02) | 3–16 | 7.28 (1.73) | 1–12 | t(293) = 8.94, p < .0001, d = .56 | .43*** |