How to Interpret Information From Graphs

Instructor: Lauren Posey

Lauren has taught intermediate reading in an English Language Institute, and she has her Master's degree in Linguistics.

Graphs are an excellent way to condense a lot of information into an easily readable format. In this lesson, you'll learn about reading and interpreting information from graphs.

Using a Graph

If you've ever taken a math or science class, chances are you've encountered some type of graph before. Graphs are a great way to take a great deal of numerically-based information, like from a scientific study, and condense it into a more easily readable format. Graphs allow people to interpret the results of a study and even make predictions about trends they might see in future data sets. For example, if you had information about the ice cream preferences of 50 men and 50 women, and wanted to see if there was a pattern, this is much easier to see in a graph format than just reading each data point separately.

Parts of a Graph

Graphs are made up of several different parts, and all of them are important to the data involved. The first part is the title. A graph title will tell you what the graph is about, and without it, the graph will probably make very little sense. Graph titles should be short and to the point, and not creative the way a short story title might be.

In addition to a title, most graphs have an x- and y-axis. The x-axis is horizontal, running along the bottom of the graph. It can be made up either of categories, such as 'ice cream flavor' or numbers, such as 'age group.' The y-axis is vertical, running along the left edge of the graph. Some very complicated graphs also have a y-axis on the right edge, but the majority only have one y-axis. This axis is made up of numbers, such as 'age' or 'number of people.'

Finally, most graphs have a legend, or key, to help you interpret results. Some simple bar graphs or line graphs might not have a legend, but if there are multiple lines or bars per category, then there will be one. Graphs are often color coded, and the legend tells you what each color represents. That way, there isn't a bunch of writing going across the graph, which would make it very difficult to read.

Types of Graphs

There are three major graph types. The first is a bar graph or histogram. These are used when the numbers being looked at are independent of each other. For example, the number of people who prefer chocolate ice cream has nothing to do with the number who prefer vanilla, and so these two data points would have separate bars. We'll look at a sample bar graph later.

The second major type of graph is a line graph, which is used to show change over time. This graph is used when the data points are connected to each other. For example, if you had data about how popular glue was over the course of 10 years, you would probably want to use a line graph.

Line graphs are ideal for mapping population
Line graph

Finally, you also have pie charts, sometimes called circle graphs. These are used to show parts of a whole. If you were showing what appliances in a home used what percentage of the power, for example, a pie chart would be ideal.

Pie charts are perfect for data out of 100 percent
Pie chart

Interpreting Data

To practice interpreting data, let's look at a bar graph:

Literacy bar graph

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