MacPotthoff 2.2 for Mac was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The application lies within Education Tools, more precisely Science. This free software for Mac OS X was originally produced by Marley Watkins.
From the developer:
MacPotthoff simultaneously and separately tests of regression slopes and intercepts for test bias analysis. Numerous methods of quantitatively assessing test bias have been proposed. These include various item metrics, construct methods, content, and predictive procedures.
You may want to check out more software for Mac, such as Genealogy Pro, sciatrope or Curvus Pro X, which might be related to MacPotthoff.