Graphing Data

Introduction and Summary

Graphs are useful because they allow the observer to make inferences about data at a glance. They are easier to read than tables of data, and they make it much easier to spot trends. Thus, it is important to understand how to make and read graphs of data.

There are many different kinds of graphs, and most of them rely on knowledge of certain statistics, such as the mean, median, mode, and range. The first section deals with the meaning of these statistics and how to find them, given a set of data.

The second section deals with a specific type of graph--the histogram. The histogram is the graph most often used to show distribution of values. This section explains how to make a frequency distribution table from a set of data, and how to make a histogram from a frequency distribution table.

Although this chapter only deals with one type of graph, it provides the tools needed to make other types of graphs; namely, it explains how to find certain statistics. In future math or statistics classes, you will use these statistics to make other types of graphs. These statistics are also useful to learn because they are frequently mentioned in reports, on the news, in commercials, etc. By learning how to compute the mean, median, mode, and range of a set of data, you will better understand statistics provided by other sources.

Learning how to make a histogram is also useful. If you ever need to present data in a report, a histogram will make it much easier to understand and more aesthetically pleasing.