What is statistics?

Statistics is the systematic study of data using mathematical – specifically, probability – theory. There are two major aspects to statistics. The first aspect of statistics is summarizing data. This is where we find numerical values that describe a set of data, including characteristics such as the center (mean or median) and spread (standard deviation or variance) of the data. These values are called descriptive statistics. What we’re doing here is fitting a probability distribution that describes the likelihood of a particular characteristic appearing in a population. Here, a population simply means a complete set of measurements of a particular characteristic – for example, the height of every person currently alive on Earth.

The second – and arguably more important – aspect of statistics is inference. Here, we try to estimate the distribution of data describing a population by computing numerical values on a relatively...