Categorical IVs

Applied Multiple Regression/Correlation Analysis for the Behavioral by Jacob Cohen, Patricia Cohen, Stephen G. West, Leona S. AikenSciences

Let us consider a fictitious investigation of background factors and altruism. The researchers have hypothesized that there are influences of population density on altruism, and have drawn samples of residents of a city and the surrounding area outside the city (noncity). (p. 344)