Charts are an efficient way of summarizing numerical data into a picture that can be quickly understood by people who may not be familiar with the subject. Comparison charts are often used in business, education and politics as a way of breaking down financial data, population figures, poll results and other quantitative data. While you do have some freedom in how to format your comparison chart, you should focus on making it as simple and easy to comprehend as possible for your reader.

Organize your data so you know exactly what you are comparing. The items being compared should be held to similar standards as well. For example, it would be confusing to compare one company's growth over a 10-year period to another company over a 2-year period. Both should be over the same time period for the chart to be valid and useful.

Pick a visual style for your comparison chart. Bar graphs are useful when analyzing statistics for two different entities or comparing different years while pie charts are efficient at showing percentages. A line graph is also effective at showing trends over a set time period.

Decide if you are using one graph or two for your chart. You may decide to have two separate graphs that can be compared to each other or you can do the comparison on a single color-coded graph.

Set the scale for your chart that will work for both entities for your comparison. For example, if you are doing a population graph for a city, your scale would likely be in millions of people with a tick on the chart for every 200,000 increase.

Color code your chart so the items being compared are visually distinctive from each other. For example, when comparing company profits from different years, one year's data could be yellow while another year is red and another is blue. This helps the reader differentiate the different data at a single glance and see what the trends are.