Table 2.
Mean-Level Change in MPQ-Estimated Psychopathic Traits From Age 17 to Age 24 (Repeated Measures Analyses of Variance)
| Age 17
|
Age 24
|
|||||||
|---|---|---|---|---|---|---|---|---|
| Trait | M | SD | M | SD | d (time) | η2 (time) | η2 (gender) | η2 (Time × Gender) |
| Fearless Dominance | ||||||||
| Total | 64.2 | 8.3 | 63.7 | 8.7 | −.06 | .00 | .05** | .03** |
| Men | 65.4 | 7.5 | 66.3 | 8.2 | .12 | .02* | — | — |
| Women | 63.3 | 8.8 | 61.8 | 8.5 | −.18 | .04** | — | — |
| Impulsive Antisociality | ||||||||
| Total | 76.0 | 12.4 | 64.7 | 11.8 | −.93 | .48** | .07** | .00 |
| Men | 79.1 | 11.4 | 68.3 | 12.1 | −.92 | .45** | — | — |
| Women | 73.8 | 12.7 | 62.1 | 10.8 | −.99 | .51** | — | — |
Note. NTotal = 920, nMen = 391, nWomen = 529. Significance levels of effects were adjusted in a mixed model in SAS to account for the dependent nature of the twin observations. d (time) and η2 (time) = Cohen’s d statistic and partial eta-squared effect sizes, respectively, for the main effect of time; η2 (gender) = percentage variance accounted for by the main effect of gender; η2 (Time × Gender) = percentage variance accounted for by the interaction between time and gender.
*
p < .01.
**
p < .001.