This PC program (diffdef.exe) accompanies the paper by Crawford, J.R., Blackmore, L. M., Lamb, A., and Simpson, S. A. (2000). Is there a differential deficit in fronto-executive functioning in Huntingtons’s Disease?. Clinical Neuropsychological Assessment, 1, 3-19. (pdf)

The program provides a method of testing for differential deficits at the group level ; i.e. it can be used to test whether the deficit exhibited by a clinical sample on Test A is significantly greater than the deficit exhibited on Test B. It does this by applying William's (1959) test for non-independent correlations: the correlation between group membership (clinical versus control) and Test A is compared with the correlation of group membership and Test B. Computing a correlation between group membership and a variable is equivalent to running a t-test or one-way ANOVA comparing the groups on the variables, i.e. the p value for the correlation is identical to the p value obtained from the t-test or ANOVA. However, by using correlations one can readily test whether the deficit on Test A is significantly greater than the deficit on Test B.

Click HERE to download the program. Your web browser is most probably configured to recognise that the file as an executable. If you encounter any problems (i.e. the browser treats it as a text file), try holding down the shift key when clicking.

Once downloaded, the program can be run by any of the normal Windows procedures i.e., by clicking on file in file manager, by using Windows start menu, or by placing on desktop etc.

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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 j.crawford@abdn.ac.uk. Further contact details are available in the footer of this page.