We will begin our discussion of descriptive statistics with univariate statistics; univariate simply means that these statistics are calculated from one variable. Everything in this section can be extended to the whole data set, but the statistics will be calculated per variable we are recording. In other words, if we had 100 observations of speed and distance pairs, we could calculate the average across the data set, which would give us the average speed and the average distance.
Descriptive statistics are used to describe and/or summarize the data we are working with. We can start our summarization of the data with a measure of central tendency, which describes where most of the data is centered around, and a measure of spread or dispersion, which indicates how far apart values are.