Math 221 – Principles of Statistics

Creating P-P Plots in SPSS

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A P-P plot is a graph that can help you decide whether your data are Normal or not. It is very similar to a Q-Q plot.

 

To create a P-P plot in SPSS:

 

1) Open a data file (in .sav or .por format) or type your data in.

 

2) In either the Data Editor window or the Output Viewer window, click on the “Graphs" menu and then on "P-P..."

 

3) Select the variable(s) of interest. Click on the little arrow next to "Variables" to move the variables (one by one) into the "Variables" box.

 

4) Make sure it says "Normal" in the "Test Distribution" box.

 

5) If you would like to add a title to your plot, click the "Titles..." button. A new dialog box appears. Enter any titles or subtitles you want to use, and click "Continue..."

 

6) Click "OK." The P-P plot appears in the Output Viewer.

 

If the little circles follow the line pretty well, with some random scatter about the line, the data are close enough to being Normal for our purposes.

 

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David E. Brown

BYU-Idaho                                            mailto:brownd@byui.edu

232 Ricks Building                         208-496-1839 voice

Rexburg, ID 83440                              208-496-2005 fax

                Please do not call me at home.