Shortening of psychological tests – assumptions, methods and doubts

In this article, on the basis of questionnaire data collected for other purposes, the Authors want to show the consequences of various methods of shortening of tests and what may result from such an action for diagnosticians, researchers and examined individuals. The research aim of the work is to show the best method of shortening of the scale of questionnaires. Will shortening of a questionnaire according to different statistical techniques bring the same results? Will the quality of shortened scales be comparable? Is any of statistical techniques better for shortening of the scale of a questionnaire? The obtained results suggest a poorly controlable effect of the methods of questionnaire shortening. Moreover creating a short version on the basis of the results collected with the use of the full version leads to obtaining a tool with unknown diagnostic and psychometric properties.