What is an alternate form reliability?
From PsychWiki - A Collaborative Psychology Wiki
An alternate form reliability is the authenticity stablished by carrying out two different forms of the same test to the same individuals. This method is convenient to avoid the problems that come from the test-retest method. With the alternate form reliability method, an individual is tested on one form of the test, and then again on a comparable second form, the inbetween time is about one week. This method is used more than the test-restest method because it has fewer related problems, including an abundance reduction in practice effects.
Example / Application
Example: Standford Prison Experiment
Application: In this experiment, two roles were given to the participants, either the role of a prisoner or a prison guard. If both roles were given to the same participant then this would have been an example of an alternate form reliability, but since the roles are given to different participants, the term does not apply to the experiment. If this concept is used correctly, a participant would be given the roles of both a prison guard and a prisoner, later, that individuals behavior during that role would be compared to the other. Since both roles are not predicted to be similar, this is the reason why alternate form reliability was not used in this experiment.
Lammers, W. J., and Badia, P. (2005). Fundamental of Behavioral Research. California: Thomson and Wadsworth.