ABSTRACT
This chapter discusses single variable data sets and various summaries for such data. Univariate data are the building blocks for multivariate data sets, but we resist the temptation to start there, preferring to take our time in the development. As mentioned, to distinguish the two: factors are used to classify values, character data is used to characterize values. Factors represent categorical data of any type. For categorial data which is ordered, R has the specialization of factor: ordered factors. Some univariate data sets may reflect the presence of underlying factors. For example, a data set on heights might best be split in two based on the gender of those measured, as on average females are shorter than males. Summarizing univariate categorial data is fairly straightforward. The basic tool is to tabulate the values and to present that information either in print or graphic form.
