Descriptive statistics is a branch of statistics that denotes any of the many techniques used to summarize a set of data. In a sense, we are using the data on members of a set to describe the set. The techniques are commonly classified as:
- Graphical description in which we use graphs to summarize data.
- Tabular description in which we use tables to summarize data.
- Parametric description in which we estimate the values of certain parameters which we assume to complete the description of the set of data.
We have two objectives for our summary:
- We want to choose a statistic that shows how different units seem similar. Statistical textbooks call the solution to this objective, a measure of central tendency.
- We want to choose another statistic that shows how they differ. This kind of statistic is often called a measure of statistical variability.