Table 2.
Means, standard deviation (SD), and estimates practice effects
| Measure | Dropouts time 1 Mean (SD) | Returnees time 1 Mean (SD) | Returnees time 2 Mean (SD) | Attrition replacements time 2 Mean (SD) | Practice effect | SE | P |
|---|---|---|---|---|---|---|---|
| Visual-spatial | 0.318 | 0.063 | <.001 | ||||
| Mental Rotation: Total Correct Part 1 [44] | 0.06 (0.99) | −0.02 (0.99) | −0.01 (1.00) | −0.27 (0.91) | 0.275 | 0.077 | <.001 |
| Hidden Figures Total Correct All Parts [45] | −0.02 (1.03) | 0.00 (0.99) | −0.20 (0.93) | −0.57 (0.87) | 0.360 | 0.074 | <.001 |
| Executive | 0.085 | 0.059 | .1404 | ||||
| D-KEFS Trails 4 time (adjusted for Trails 2 and 3, log transformed) | −0.09 (0.95) | –0.01 (1.01) | −0.07 (0.98) | −0.17 (1.14) | 0.083 | 0.093 | .339 |
| D-KEFS Category Switching Accuracy (adjusted for verbal fluency) | −0.02 (1.04) | −0.01 (0.99) | −0.04 (1.02) | −0.16 (1.18) | 0.106 | 0.096 | .222 |
| Stroop: Interference Score (adjusted for color and word) [46] | −0.14 (0.97) | 0.03 (1.00) | −0.26 (1.05) | −0.358 (1.08) | 0.064 | 0.090 | .4759 |
| Short-term/working memory | 0.226 | 0.046 | <.001 | ||||
| WMS-III Digit Span: Forward Raw Score | −0.01 (1.04) | 0.01 (0.99) | −0.05 (0.98) | −0.21 (1.03) | 0.152 | 0.084 | .071 |
| WMS-III Digit Span: Backward Raw Score | 0.01 (1.04) | 0.00 (0.99) | −0.02 (0.96) | −0.28 (0.77) | 0.258 | 0.067 | .001 |
| WMS-III Spatial Span: Total Trials Passed | −0.05 (1.05) | 0.03 (1.00) | −0.11 (1.01) | −0.51 (0.96) | 0.388 | 0.080 | <.001 |
| WMS-III Spatial Span: Total Trials Passed Backward | −0.12 (0.99) | 0.03 (1.00) | −0.19 (0.99) | −0.49 (0.91) | 0.268 | 0.077 | <.001 |
| WMS-III Letter-Number Sequencing: Total Score for Trials Passed | −0.04 (0.98) | 0.01 (1.00) | −0.18 (0.97) | −0.37 (0.95) | 0.181 | 0.080 | .029 |
| Reading Span: Total Score Ascending | 0.00 (1.06) | 0.00 (0.98) | −0.13 (0.94) | −0.24 (1.00) | 0.108 | 0.082 | .186 |
| Episodic memory | 0.222 | 0.054 | <.001 | ||||
| CVLT Total of Trials 1–5 | −0.10 (1.00) | 0.03 (1.00) | 0.04 (1.03) | −0.23 (1.02) | 0.236 | 0.085 | .007 |
| CVLT Short Delay Free Recall | −0.09 (0.99) | 0.02 (1.01) | −0.01 (1.05) | −0.21 (1.12) | 0.186 | 0.092 | .039 |
| CVLT Long Delay Free Recall | −0.11 (1.02) | 0.02 (0.99) | 0.04 (1.03) | −0.11 (1.04) | 0.125 | 0.086 | .158 |
| WMS-III Logical Memory: Immediate Recall Story Units Total Score | −0.07 (1.00) | 0.01 (0.99) | −0.07 (1.01) | −0.37 (0.95) | 0.293 | 0.079 | <.001 |
| WMS-III Logical Memory: Delayed Recall Story Units Total Score | −0.09 (1.04) | 0.02 (0.99) | −0.11 (1.03) | −0.39 (1.00) | 0.256 | 0.083 | .003 |
| WMS-III Visual Reproduction: Immediate Recall Total Score | −0.16 (1.01) | 0.03 (1.00) | 0.04 (1.02) | −0.16 (0.98) | 0.166 | 0.082 | .055 |
| WMS-III Visual Reproduction: Delayed Recall Total Score | −0.17 (1.04) | 0.03 (0.99) | 0.12 (0.99) | −0.21 (0.93) | 0.295 | 0.078 | <.001 |
| Processing speed | 0.197 | 0.057 | .002 | ||||
| D-KEFS Trails 2 time (log transformed) | −0.07 (1.00) | 0.01 (1.00) | 0.03 (1.05) | −0.2 (1.03) | 0.213 | 0.086 | .018 |
| D-KEFS Trails 3 time (log transformed) | −0.12 (1.04) | 0.03 (1.01) | −0.01 (1.01) | −0.26 (1.04) | 0.223 | 0.086 | .010 |
| Stroop: Raw Word Score [46] | 0.06 (1.04) | −0.01 (1.00) | −0.31 (0.99) | −0.44 (0.92) | 0.148 | 0.076 | .076 |
| Stroop: Raw Color Score [46] | 0 (1.02) | −0.01 (0.99) | −0.29 (0.98) | −0.49 (0.91) | 0.202 | 0.075 | .015 |
| Abstract Reasoning | 0.159 | 0.087 | .066 | ||||
| WASI Matrix Reasoning Raw Score | −0.11 (0.96) | 0.02 (1.00) | −0.03 (1.01) | −0.21 (1.05) | 0.159 | 0.087 | .066 |
| Verbal fluency | 0.085 | 0.057 | .254 | ||||
| D-KEFS Letter Fluency FAS total correct | 0.05 (0.98) | 0.00 (1.00) | −0.11 (0.99) | −0.18 (1.09) | 0.088 | 0.088 | .301 |
| D-KEFS Category Fluency Animal/Boys total correct | −0.04 (1.02) | 0.01 (1.01) | −0.01 (1.02) | −0.11 (1.04) | 0.082 | 0.086 | .338 |
Abbreviations: D-KEFS, Delis-Kaplan Executive Function System [47]; CVLT, California Verbal Learning Test [48]; WASI, Wechsler Abbreviated Scale of Intelligence [49]; WMS-III, Wechsler Memory Scale-III [50].
NOTE. All scores have been adjusted by regressing out age 20 GCA scores and then converted to z-scores based on wave 1 means and standard deviations (SDs). Standard errors (SEs) were calculated using bootstrap resampling, and P values were calculated using permutation testing. Practice effect values represent the expected gain in performance resulting from repeat testing. These values can be subtracted from returnees' time 2 scores to adjust follow-up tests for the effects of practice.