families had at least two P300 measures from both offspring (66.7% of low paternal risk, 57.1 % of intermediate paternal risk, and 52.3 % of paternal AAB groups, a nonsignificant difference), χ2(2, N = 201) = 2.95, p= .229). In addition to all of these analyses of the effects of missing data being nonsignificant, they all resulted in effect sizes that are conventionally regarded as being in the small effect range (J. Cohen, 1988; .039 ≤ Cohen’s w ≤.121). Given these patterns of missing data and the small effect sizes represented, it appears that there were no important systematic biases in attrition related to paternal history. This is consistent with the data missing at random.
