Suppose you find a restriction in your study of IQ scores and school achievement at a selective private school. Restricting the range is likely to do what to the correlation coefficient?
a. Increase the size
b. Underestimate the strength
c. Have no effect
d. Change the sign
This website may help:
It's confusing at first because it gives you two scenarios - one when there is a ...
Help with a correlation coefficient is given.