Tutorial:Q-Q Plot

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Summary

Q-Q plot is a graphic method to test whether or not a dataset follows a given distribution. In a Q-Q plot, observed values on X axis and expected values on Y axis are shown. If all the scatter points are close to the reference line, we can conclude that the dataset follows the given distribution.

Image:Graph_Gallery_Q-Q_Plot_9.png

Minimum Origin Version Required: Origin 8.1 SR0

What you will learn

  • How to create a normal Q-Q plot
  • How to change the color and shape of the symbol
  • How to change the color of the line

Steps

This tutorial is associated with the Statistical and Specialized Graphs project:\Samples\Statistical and Specialized Graphs.opj. (If you don't have the OPJ, you can also download the data from here)

  1. Open the Statistical and Specialized Graphs project, open the folder Statistical and Specialized Graphs: Statistical: Probability, QQ Plot in the Project Explorer. Activate worksheet Q-Q Plot Data, highlight column A and right-click to select Set As: Y from the context menu.

    Image:Graph_Gallery_Q-Q_Plot_2.png
  2. Add a long name to this column, say Normal Random Values.

    Image:Graph_Gallery_Q-Q_Plot_3.png
  3. Highlight this column and select Plot: Statistics: Q-Q Plot from the Origin main menu to open the plot_prob dialog. In this dialog, change Score Method to Benard.

    Image:Graph_Gallery_Q-Q_Plot_4.png
  4. Click the OK button to create a normal Q-Q plot with column A.
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