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# No values in correlation matrix

Hello

I created a correlation matrix via PROC CORR and found that the variable FF, which is dummy variable, has no values with 3 other variables (which are continous variables). I attached here the result as I got

Any clue why this is happened?

Thanks a lot!

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Solution
‎07-06-2016 12:37 AM
SAS Super FREQ
Posts: 3,752

## Re: No values in correlation matrix

This would happen if your FF variable is constant. The formula for the Pearson correlation has a denominator that contains the variance of the two variables. A constant variable has variance=0, which makes the correlation coefficient undefined. For example:

``````data a;
set sashelp.class;
c = 1;    /* constant value */
run;

proc corr data=a;
run;``````

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Solution
‎07-06-2016 12:37 AM
SAS Super FREQ
Posts: 3,752

## Re: No values in correlation matrix

This would happen if your FF variable is constant. The formula for the Pearson correlation has a denominator that contains the variance of the two variables. A constant variable has variance=0, which makes the correlation coefficient undefined. For example:

``````data a;
set sashelp.class;
c = 1;    /* constant value */
run;

proc corr data=a;
run;``````

☑ This topic is solved.