Download of rProphecy 2.0.2 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The program belongs to Education Tools. We recommend checking the downloaded files with any free antivirus. The actual developer of this free software for Mac is Marley Watkins.
From the developer:
rProphecy is a standalone Mac program that calculates the Spearman-Brown 'Prophecy' formula that estimates the reliability of a test if its number of items is altered. You can calculate the modified test reliability by entering the current test reliability and the proportion of change. Alternatively, you can calculate the proportion of change needed by entering the current and modified test reliability.
You may want to check out more Mac applications, such as FRS Money Math, FRS Clocks and Time or ExamView Pro, which might be related to rProphecy.