Chapter 8

bivariate correlation

an association that involves exactly two variables

effect size

the strength of a relationship between two more more variables

statistically significant

a correlation that is unlikely to have come from a population in which the association is zero

restriction of range

this can occur if there is not a full range of scores on one of the variables in the association, so the correlation appears smaller than it really is

curvilinear relationship

a relationship between two variables that is not a straight line

the directionality problem

states the method must ensure that the cause variable preceded the effect variable

the third-variable problem

states that there must be no plausible alternative explanation for the relationship between the two variables

spurious relationship

the bivariate correlation is there, but only because of some third variable

moderator

when the relationship between two variables changes depending on the level of another variable, the other variable is called this