Association and correlation between numeric variables, in SPSS
Bro. David E. Brown, BYU–Idaho Dept. of Mathematics
February 2, 2012
To use the following instructions, your data need to be two numeric (Scale) variables.
1. Start SPSS and enter your data or open your data file.
2. Make any necessary adjustments in the Variable View. Pay particular attention to the Measurement levels of your variables. They must be scale for the following to work.
3. To make scatterplots. . .
• In the Graphs menu, click Legacy dialogs. A submenu will appear.
• In the submenu, click Scatter/Dot, which is near the bottom.
• The Scatter/Dot selector box appears.
• Select Simple Scatter and click Define. The Simple Scatterplot dialog appears.
• Move to the Y Axis: box the name of the variable you want on your vertical axis. (For association
and correlation, it does not matter which variable you put on the y-axis and which you put on
the x-axis.)
• Move to the X Axis box the name of the variable you want on your horizontal axis.
• If you want, you can click Titles... to add a title, subtitle, and so on; click Continue to return
to the Simple Scatter dialog.
• Click OK. The SPSS Output Viewer appears, with your scatterplot in it.
4. To calculate correlation coefficients. . .
• In the Analyze menu, click Correlate. A submenu will appear.
• In the submenu, click Bivariate... The Bivariate Correlations dialog will appear.
• Put in the Variables: box the names of the variables whose correlation coefficient(s) you want
to calculate. (If you put more than two in, SPSS will calculate the correlation coefficient for every
pair of variables you’ve put in the Variables: box.)
• You will see check boxes for three kinds of correlation coefficient. Make sure there’s a check mark
next to Pearson’s correlation coefficient.
• Farther down, you’ll see a check box for Flag significant correlations. Now, SPSS will test
the hypothesis H0 : ρ = 0 for each variable. If there is a check mark in the Flag significant
correlations box, then SPSS will put an asterisk (*) next to any correlation coefficient for which
the P-value is less than 0.05. SPSS will put two asterisks (**) next to any correlation coefficient
for which the P-value is less than 0.01. If you don’t want these asterisks, clear the check mark by
clicking on it.
• Click OK. SPSS puts a Correlations table in the Output window. There will be a set of rows in
the table for each variable you put in the Variables: box.
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– The leftmost column tells you which variable the given set of rows is for and the name(s) of
the type(s) of correlation coefficient calculated. It also tells which row the P-value of the test
of H0 : ρ = 0 is in, as well as which row the number n of data points is in (except it says “N”
instead of “n.”
– The cells in the next two columns contain the following information:
∗ The coefficient of correlation for the variables of the row and column in which the cell
resides
∗ The P-value for the test of H0 : ρ = 0, if the row variable is different from the column
variable
∗ The number of data points used to calculate the correlation coefficient.
As always, if you have questions, please ask them!
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