These programs for PCs accompany the paper: Crawford, J. R. , Garthwaite, P. H. & Gault, C. B. (2007). Estimating the percentage of the population with abnormally low scores (or abnormally large score differences) on standardized neuropsychological test batteries: A generic method with applications. Neuropsychology, 21, 419-430. (pdf)
In neuropsychological assessment a fundamental question is whether an individual's test scores are abnormally low. Relatedly, it is important to estimate the abnormality of differences between an individual's scores. However, neuropsychological testing involves multiple tests. For example, suppose an abnormal score is defined as a score exhibited by less than 5% of the general population and that an individual exhibits two abnormally low scores on a test battery of 10 tests. It would be useful to know the base rate in this situation; that is, what percentage of the general population would be expected to exhibits this number of abnormal tests. The same holds when the concern is with abnormal differences between tests, i.e., if a patient exhibits three abnormal differences between pairs of tests in a battery, what percentage of the general population is expected to exhibit this number of abnormal pairwise differences?
The generic program (PercentAbnormK.exe) uses Monte Carlo simulation to estimate (A) the percentage of the population expected to exhibit j or more abnormally low scores on a standardized test battery, (B) the percentage expected to exhibit j or more abnormally large deviations from individuals' mean scores on a battery, and (C) the percentage expected to exhibit j or more abnormally large pairwise differences between tests in a battery.
Two further programs are available; these are specifically tailored to analyzing WAIS-III and WISC-IV Index scores (WAISIII_Percent_Abnorm.exe and WISCIV_Percent_Abnorm.exe). The programs take an individual's scores on the four WAIS or WISC Indices as input. The program calculates the abnormality of the Index scores and differences between Index scores. The number of scores and score differences meeting the user-defined criterion for abnormality is then recorded along with the percentage of the general population expected to exhibit this number (or more) of abnormal scores or score differences.
Click here to download all three programs as one zip file.
Click here to download PercentAbnormK.exe as an executable (456Kb) or to here download a zipped version of the program (229KB).
Click here to download WAISIII_Percent_Abnorm_v2.exe as an executable (456Kb) or here to download a zipped version of the program (229KB). Please note: this is version 2 of the program (hence v2 extension) the original had a bug which is now fixed.
Click here to download WISCIV_Percent_Abnorm_v2.exe as an executable (456Kb) or here to download a zipped version of the program (229KB). Please note: this is version 2 of the program (hence v2 extension) the original had a bug which is now fixed.
Your web browser is most probably configured to recognise that the file is executable. If you have any problems (i.e. the browser treat it as a text file), hold down the shift key when clicking. If your network does not allow downloads of executables then downloading the zip file is a solution.
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 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.
