This PC program (tvardiff.exe) accompanies the paper: Garthwaite, P.H. and Crawford, J. R. (2004)“The distribution of the difference between two t-variates”.  Biometrika, 91, 987-994. 

The program allows the user to test for a difference between two t-variates.  The most common application of this method will be to test whether the difference between an individual's standardized scores on two variables (X and Y) is significantly different from the differences observed in a control sample. 

Click here to download the program (435Kb). A zipped version is also available.

Your web browser is most probably configured to recognise that the files are executable. If you have any problems (i.e. the browser treats them as text files), hold down the shift key when clicking.  As the file is an executable, you may get a warning to this effect from your web browser; the warning can be ignored.Once downloaded, the programs can be run by any of the normal Windows procedures i.e. by clicking on file in File Manager or by placing on desktop etc.

The test on the difference between two t-variates has also been incorporated into a program used to test for the presence of classical and strong dissociations (for use in single-case studies). Click here for details of this additional program.

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The author of this software (John R Crawford) and the University of Aberdeen make no representations about the suitability of the software or about any content or information made accessible by the software, for any purpose.

The software is provided 'as is' without express or implied warranties, including warranties of merchantability and fitness for a particular purpose or noninfringement.

The software is provided gratuitously and, accordingly, the author shall not be liable under any theory or any damages suffered by you or any user of the software.

If there are any problems please e-mail me at Further contact details are available in the footer of this page.