condition that exists when independent variables are highly correlated with each other. In the presence of multicollinearity, the estimated regression coefficient may be unreliable. The presence of multicollinearity can be tested by investigating the correlation (r) between the independent variables.

existence of a relationship between the independent variables in a multiple regression -that is, a change in one variable causes a change in the other variable. Together, they cause a change in the dependent variable(s) .

the presence of independent variables in regression analysis that are associated to each other (having some degree of correlation). The presence of multicollinearity implies that there are fewer data to explain the dependent variable.