TABLE 2.
Distributions of Neurocognitive Test Scores in the Total Sample Compared to the Normal Distribution
| z Score | ||||
|---|---|---|---|---|
| ≤ −2 | > −2 and ≤ −1 | > −1 and ≤1 | >1 | |
| Normal distribution | 2.3 | 13.7 | 68.2 | 15.8 |
| General cognitive ability | ||||
| DAS-II Verbal | 17 | 19 | 57 | 7 |
| DAS-II Nonverbal Reasoning | 15 | 24 | 56 | 5 |
| Language | ||||
| OWLS Listening Comprehension | 19 | 27 | 50 | 4 |
| OWLS Oral Expression | 19 | 22 | 52 | 6 |
| Executive function | ||||
| DAS-II Working Memory | 18 | 18 | 61 | 4 |
| NEPSY-II Auditory Attention | 23 | 21 | 56 | 0 |
| NEPSY-II Auditory Response Set | 20 | 28 | 48 | 4 |
| NEPSY-II Inhibition Inhibition | 34 | 23 | 40 | 3 |
| NEPSY-II Inhibition Switching | 27 | 29 | 37 | 6 |
| NEPSY-II Animal Sorting | 29 | 30 | 38 | 3 |
| Processing speed | ||||
| NEPSY-II Inhibition Naming | 31 | 20 | 41 | 8 |
| Visual perception | ||||
| NEPSY-II Arrows | 26 | 22 | 46 | 6 |
| NEPSY-II Geometric Puzzles | 17 | 22 | 57 | 4 |
| Fine motor function | ||||
| NEPSY-II Visuomotor Precision | 21 | 35 | 38 | 7 |
| Achievement | ||||
| WIAT-III Word Reading | 14 | 16 | 57 | 13 |
| WIAT-III Pseudoword Decoding | 16 | 18 | 57 | 9 |
| WIAT-III Spelling | 14 | 21 | 54 | 11 |
| WIAT-III Numeric Operations | 17 | 24 | 54 | 5 |
| Maximum column N | 180 | 395 | 298 | 873 |
Data are presented as percentages unless otherwise indicated. Maximum N = 873. OWLS, Oral and Written Language Scales. In χ2 goodness-of fit tests, distributions of scores for all measures differed significantly from the normative expectation at P < .001.