Political scientists generally derive their quantitative methodologies from two disparate traditions: econometric or psychometric. The psychometric tradition has made a lasting impact on political analysis through attention to issues of measurement. Measurement issues are particularly troublesome to political scientists because many interesting concepts are either latent or multidimensional. On the other hand, the econometric tradition has provided political scientists with a means of coping with macrolevel phenomena. In studying macrophenomena, the problem of few cases (there is only one American economy, for example) is handled by using longitudinal analysis. Econometrics provided tools for coping with challenges that longitudinal analysis posed for regression analysis.