Attitudes on related but overlapping foreign-policy issues collapse into a single underlying dimension

Evidence

Notice that Equation 1 includes three variables to represent the domain of foreign affairs, not four. In preliminary analyses, we found that attitudes toward U.S. involvement in Central America and attitudes toward aid to the Contras were highly correlated. People who opposed aid to the Contras were likely to oppose U.S. involvement in Central America, and those who favored aid to the Contras were likely to favor U.S. involvement in Central America (r=.42). These two attitudes correlated more weakly with views on isolationism and on U.S. strength (.10<r<.25), and these latter two attitudes were uncorrelated with each other (r= .04). Therefore, in the analysis of priming, we averaged attitudes toward aid to the Contras and toward U.S. intervention in Central America into a single measure. — John T. Jost and Jim Sidanius, Political Psychology, 1595

Categorization

• DEFINE: Illustrates the standard practice of combining highly correlated survey items into a single scale before analysis.