Linear Correlation?

#2
Suppose you perform a correlation between IQ scores and School Performance. Suppose this correlation turns out to be r = + 0.70. Squaring this correlation would allow us to see how much the variance in school performance is accounted by an IQ, specifically 49% ( R^2 = .49). So we can conclude that about 50% of the variance in school performance is attributed to IQ scores alone, while the other 50% might be due to other factors unknown, perhaps environment, type of school, study habits, etc.