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# Data Representation and Interpretation Study Guide: GED Math

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Updated on Mar 23, 2011

Practice problems for these concepts can be found at:

Data Analysis, Statistics, and Probability Practice Problems: GED Math

### Data Representation and Interpretation

The GED exam will test your ability to analyze graphs and tables. It is important to study each graph or table very carefully before reading the question. This will help you to process the information that is presented. It is extremely important to read all of the information presented, paying special attention to headings and units of measure. Here is an overview of the types of graphs you will encounter:

### Circle Graphs or Pie Charts

Circle graphs or pie charts show how the parts of a whole relate to one another. A pie chart is a circle divided into slices or wedges—like a pizza. Each slice represents a category.

### Line Graphs

Line graphs show how two categories of data or information (sometimes called variables) relate to one another. The data is displayed on a grid and is presented on a scale using a horizontal axis and a vertical axis for the different categories of information the graph is comparing. Usually, the data points are connected together to form a line so that you can see trends in the data, or how the data changes over time. Therefore, often you will see line graphs with units of time or the word time on the horizontal axis.

Line graphs are frequently used to show the results of a scientific experiment. The variable that the scientist is measuring and tracking is often called the dependent variable. It is usually measured on the vertical axis of a graph. The horizontal axis is usually measuring time, so you can see how the data changes over time.

### Bar Graphs

Like pie charts, bar graphs show how different categories of data relate to one another. A bar represents each category. The length of the bar represents the relative frequency of the category—compared to the other categories on the graph.

Both pie charts and bar graphs are used to compare different categories of data. So when you have data to graph, how do you decide which kind of graph to use? Think about what your purpose is. If your purpose is to compare the absolute values of each category, then a bar chart is probably better because the amounts of each category are shown in comparison to each other. If your purpose is to show how each part relates to the whole, a pie chart is probably better.