14  Descriptive statistics

14.1 Introduction

We begin the proper data analysis with the descriptive analysis, the analysis type that deals with describing the data at hand without projecting out findings to the rest of the population. The descriptive analysis method used is dependent on the type of variable involved.

Numeric variables are usually described using two statistics, a measure of central tendency and a measure of dispersion. Graphically, numeric data can be presented in a number of ways including histograms, boxplots and scatter diagrams.

Categorical variables on the other hand are usually described using frequency tables and contingency tables. Additionally, they can be graphically presented as bar charts.