Describing the Political World: Quantitative Analysis

This chapter introduces quantitative analysis, with a focus on descriptive statistics, which are used to describe the characteristics of a sample or population. Statistics can be univariate, involving a single variable; bivariate, describing the relationship between two variables; or multivariate, examining three or more variables.

Three important types of descriptive statistics are measures of central tendency, measures of dispersion, and measures of association. All of these types of measures are focused on describing a set of data. Measures of central tendency refer to the average or central trend within the data. Measures of dispersion refer to how well the measure of central tendency reflects the dispersion. Measures of association describe how different variables are related to each other. There are different measures that can be used with nominal, ordinal, or interval-ratio variables. The chapter gives numerous examples of the different possible measures and the logics involved in their use.