INTRODUCTION TO MULTIVARIATE ANALYSIS
 

Multivariate analysis, the analysis of more than two variables at a time, opens up a world of exciting possibilities for the quantitative data analyst.  Having discovered a (bivariate) relationship between two variables--gender and income, for example--we now proceed to understand that relationship ever more fully.  If you recall the Chapter 4 discussion of causation, and specifically the discussion of spuriousness, you will now have an opportunity to put knowledge to work.

Women earn less than men.  However, women are also more likely than men to work part-time.  It makes sense that part-time workers would earn less than those working full-time.  Does the variable, full-time/part-time, account for the fact that women earn less?  Or does gender discrimination play a role?  People have opinions about such things, but you will now be able to resolve the matter through data analysis.