Evidence of nonrandom differences in group means occurs when the variance between groups is _ the variance within groups.Why are scatterplots necessary when investigating the relationship between quantitative variables?r is always greater than or equal to and less than or equal to . Perfect negative association is present when r = .
Perfect positive association is present when r = . Between r = -0.56 and r = +0.46, the stronger correlation is __.Besides linearity, what conditions are needed to infer population slope ? (3 more conditions)? Besides linearity, what conditions are needed to infer population correlation coefficient ? (2 more conditions)?