• Print |
• E-mail  |
• Bookmark

Compute biserial, point biserial, and rank biserial correlations

PURPOSE:

Computes biserial, point biserial, and rank biserial correlations between a binary and a continuous variable.

REQUIREMENTS:

Base SAS Software.

USAGE:

Follow the instructions in the Downloads tab of this sample to save the %BISERIAL macro definition. Replace the text within quotes in the following statement with the location of the %BISERIAL macro definition file on your system. In your SAS program or in the SAS editor window, specify this statement to define the %BISERIAL macro and make it available for use:

   %inc "<location of your file containing the BISERIAL macro>";

Following this statement, you may call the %BISERIAL macro. See the Results tab for an example.

The required arguments for the %BISERIAL macro are as follows:

data=

SAS data set to be analyzed.

binary=

Name of dichotomous variable which must be numeric with values 0 and 1.

contin=

Name of continuous variable.

out=

Output data set name.

DETAILS:

The %BISERIAL macro produces only an output data set.

LIMITATIONS:

No error checking is done. Be sure that data set and variable names exist and are properly spelled.

MISSING VALUES:

Observations with missing values of the binary or the continuous variable are excluded.

REFERENCES:

Helena Chmura Kraemer, 1982, "Biserial Correlation", Encyclopaedia of Statistical Sciences, Volume 1, Wiley, pages 276-279.

EXAMPLE:

In the following statements, correlations are computed between the binary variable, X1, and the continuous variable LENGTH. Since X1 does not have values 0 and 1, the variable EVENT is created and used in the %BISERIAL macro. The data set OUT1 contains the correlations.

    data k;
     length x1 $ 1;
     input x1 length;
     event=(x1='y');
     cards;
    y 14.8
    n 13.8
    y 12.4
    y 10.1
    y 7.1
    y 6.1
    n 5.8
    y 4.6
    n 4.3
    n 3.5
    n 3.3
    y 3.2
    y 3.0
    n 2.8
    n 2.8
    n 2.5
    y 2.4
    y 2.3
    y 2.1
    n 1.7
    n 1.7
    n 1.5
    n 1.3
    n 1.3
    n 1.2
    n 1.2
    n 1.1
    y 0.8
    n 0.7
    n 0.6
    n 0.5
    n 0.2
    n 0.2
    y 0.1
    ;

    /* Define the BISERIAL macro */
    %inc "<location of your file containing the BISERIAL macro>";
    
    %biserial(data=k, contin=LENGTH, binary=EVENT, out=out1);

    proc print data=out1 label noobs;
     title 'Point Biserial, Biserial and Rank Biserial Correlations';
     run;

RESULTS:

                 Point Biserial, Biserial and Rank Biserial Correlations

                               Point                   Rank
                             Biserial    Biserial    Biserial
                               Corr        Corr        Corr

                              0.36149     0.45369     0.43590

Right-click on the link below and select Save to save the %BISERIAL macro definition to a file. It is recommended that you name the file biserial.sas.

Download and save biserial.sas

Operating System and Release Information