APPENDIX V: Histograms

Histograms (also called frequency distributions) show the frequency of different values in a set of data. They're often used to display data in conjunction with t-Tests or Anova and can be useful in determining whether data are distributed normally.

• If you wanted to create a histogram for the set of numbers shown in column A below (data available here), you might choose the following categories or ranges of values: values from zero to 2, values from greater than 2 to 4, etc. These categories could be listed as 0 – 2, >2 – 4, >4 – 6, >6 – 8, >8 – 10.
• To set up those categories, type in a second column of numbers called Categories or Bins as shown below. You are now ready to create a histogram.
  
  
  
  
• Once the data are entered as shown, select Histogram from the Data Analysis option under the Tools menu. Click OK.
  
  
  
  
• In the Input Range box, drag down the column containing the data; in the Bin Range box, drag down the column containing the Bin categories. Click OK.
• In your spreadsheet, you should see the output shown in columns A and B below:
  
  
  
  
  
• I recommend adding another column (column C above) to use as x-axis labels that will clearly show the range of values that correspond to the columns in your histogram.
• Now you're ready to make your graph. Click and drag down your frequency data column B (I recommend skipping the last value 0 that corresponds to the "More" category in column A), click Insert, Column, choose the upper left Column type. You should see something like this:
  
  
  
  
  
• To add your categories in column C as x-axis labels, right click your graph, click Select Data, click Edit under the Horizontal (Category) Axis Labels, then drag down your labels in column C. Your screen should now look like the screenshot below. Click OK.
  
  
  
  
  
• Now all that's left is to add axis labels and adjust the formatting of your graph. You may find these directions useful. Once completed, your histogram should look something like this: