Table 2.
Untransformed and transformed MZ and DZ co-twin means and standard deviations for SCQ and SRS scores, across extreme group and non-ASD twins.
| Untransformed Means | Transformed Means | ||||||||
|---|---|---|---|---|---|---|---|---|---|
|
| |||||||||
| Measure | Sub-sample | Twin Pairs | Cut Scores | MZ proband | MZ cotwin | DZ proband | DZ cotwin | MZ cotwin | DZ cotwin |
| MZ/DZ | M (z) | M (z) | M (z) | M (z) | M | M | |||
| SCQ (raw score) | |||||||||
| ASD | 52/232 | - | 23.3 (3.7) | 20.2 (3.0) | 22.4 (3.5) | 10.1 (1.0) | .83 | .29 | |
| SCQ 99th% | 45/168 | 21 | 26.8 (4.4) | 20.9 (3.2) | 26.2 (4.2) | 10.8 (1.2) | .73 | .27 | |
| SCQ 97th% | 50/217 | 15 | 25.1 (4.0) | 20.8 (3.2) | 23.8 (3.8) | 10.5 (1.1) | .78 | .29 | |
| SRS (T-score) | |||||||||
| ASD | 26/126 | - | 81.9 (3.2) | 77.3 (2.7) | 86.2 (3.6) | 59.3 (0.9) | .85 | .26 | |
| SRS ≥99th% | 17/88 | 81 | 95.0 (4.5) | 83.5 (3.3) | 95.7 (4.6) | 60.8 (1.1) | .74 | .24 | |
| SRS ≥97th% | 21/113 | 70 | 88.4 (3.8) | 82.9 (3.3) | 89.6 (4.0) | 61.6 (1.2) | .86 | .30 | |
Note. SCQ cutoffs are based on raw scores, while SRS cutoffs are based on T-scores. ASD and non-ASD groups are derived from clinical diagnoses. Untransformed means are presented in raw score metric and after computing z-scores for all twins using the population mean and standard deviation. Transformed means divide co-twin z-scores by proband z-scores. Thus, transformed proband means are 1.0 for both zygosities.