The study  of statistics involves the collection, analysis, and interpretation of data.  Statistics themselves are the data being studied from samples of a population.  A population is an entire set of data from which we will be collecting data.  Examples of populations include the age of residents of the United States, the length of all the fish in a pond, the height of children in middle school.  A sample is a subset of a population.  We use these samples to draw inferences about the entire population.  This is especially useful in cases where it would be extremely difficult, if not impossible, to get data from an entire population.  Drawing conclusions from samples may introduce error.

Statistics can be used to describe the data.  We use measures of central tendency to describe the middle of a set of data.  Measures of central tendency include mean, median, and mode.

We also need to understand statistical variation, sometimes thought of as statistical dispersion.  Even though two sets of data may have the same mean, the average distance data is from the mean (deviation) gives us further information about the data.

It is also useful to graphically represent statistical data.  Graphical representations, including box-and-whisker plots, can help us see measures of central tendency and the spread of the data.