The most commonly experienced sleep disorder is

In the third stage of friendship, which begins toward the end of middle childhood, friendship is based on _____________

a) time spent together b) mutual trust c) others' behavior d) psychological closeness

If robs= +.40, then _____ percent of the variance in the scores of one variable is associated

with variation in the other variable. a. 40 b. 60 c. 16 d. 8