If the correlation between the IQs of identical twins is .86,then,in any group of identical twins,what percent of the variation in the "Y" twins' IQs is accounted for by knowing
The IQs of their identical siblings (the "X's")?
A) 22
B) 43
C) 74
D) 86

Question

Quizplus · Accepted Answer

The correlation coefficient squared (r^2) gives the proportion of variance in the Y variable (IQ of the second twin) accounted for by the X variable (IQ of the first twin). Therefore, r^2 = 0.86^2 = 0.7396 or 74% of the variation in the Y twins' IQs is accounted for by knowing the IQs of their identical siblings.

If the Correlation Between the IQs of Identical Twins Is