The following analysis is based on a review of the DiSC website as well as answers to specific questions that were posed to the publisher.
What does the test purport to measure?
The RMP is clear in that it is intended to measure an individual’s motives – what Professor Steven Reiss called basic desires or psychological needs. According to the theory of 16 basic desires, our motives determine our values, influence the development of our personality traits, and predict our behavior.
The DiSC measures patterns of behavior. It does not measure motivation.
How was the test developed?
The RMP was developed scientifically. Professor Reiss did not use an a priori approach in developing the RMP. That is, he did not start with preconceived ideas about the universal goals that motivate everybody. Rather, he developed the RMP using an empirical (scientific) approach. He devised a questionnaire with 328 items about what might motivate someone and then used factor analysis to interpret the results. Three exploratory factor studies and one confirmatory factor study, each with a different sample of subjects, revealed that 128 items could be grouped into distinct scales. In short, Professor Reiss allowed data to determine the motives.
The DiSC is built on William Marston’s belief that the behavioral expression of emotions can be categorized into four primary types. Walter V. Clarke developed a Self Discription assessment based on Marston’s model of behavior, and then John Geier created the DiSC using the Self Discription as well as information gathered through clinical interviews. In response to a direct question, the publisher stated: “The DiSC does not have any history utilizing empirical approach.”
What results does the test produce?
The RMP measures a test taker’s intensity of motivation from weak to strong for each of the 16 scales. While previous motivational theorists spoke in general terms of motivation and personality, Professor Reiss was the first to devise a conceptual platform that connects motives to specific traits. According to Professor Reiss, intensity of motivation is central to understanding the development of personality traits. While everyone is motivated by the same 16 goals, what makes us individuals is how much we want of each of those goals. In short, the RMP provides an assessment of personality traits along a continuum, which is the method preferred by researchers.
The DiSC classifies a test taker into one of four distinct types. The types are based on Marston’s notions about behavioral differences among people and not on scientific data suggesting that these four types can explain individuality. Individual differences – whether we are measuring personality traits such as sociability or physical traits such as height – are better represented by a continuum than a category.
Has the test been independently validated?
Test authors and test publishers provide data to demonstrate the reliability and validity of their assessments. This is true for both the RMP and the DiSC. Only the RMP, however, has been validated by independent researchers. Published studies have been conducted by researchers in Canada (Professor Thomas Mengel of the University of New Brunswick), Finland (Professor Päivi Mayor of Tampere University of Applied Sciences, Marjaana Herlevi), Poland (Professor Agata Chudzicka-Czupala of the SWPS University of Social Sciences and Humanities, Agata Basek), and the United States (Professor Kenneth R. Olson of Fort Hays University).
In response to a direct question, the publisher of the DiSC stated: “Although we do offer assessments to researchers who are interested in independent DiSC research, we do not have any who have submitted their validity/reliability results for publication in academic journals.”
Can the test be used globally?
The RMP is available in 19 languages. According to the publisher, the DiSC is available in 11 languages.
Who was the test developer?
The RMP was developed by Professor Steven Reiss for the purpose of advancing knowledge about human nature, not for commercial reasons. Professor Reiss was educated at Dartmouth College, Yale University, and Harvard University. In addition to the RMP, he developed the Anxiety Sensitivity Index, a test that has been translated into more than 20 languages and that is widely used in the assessment of anxiety disorders. His work in the field of developmental disabilities was recognized with five national awards, and he gave invited talks in more than ten countries. Professor Reiss’s obituary was published in the American Psychologist, an honor that is accorded to very few psychologists – only those who are considered to have made significant advances in the field.
William Marston, who was educated at Harvard University, wrote a popular psychology book putting forth his ideas about categorizing people into one of four types. Marston also was known as the inventor of the female superhero, Wonder Woman. Walter V. Clarke was an industrial psychologist who worked in Human Resources and who was seeking to develop a tool for personnel selection. John Geier majored in speech at Northwestern College and then earned a doctorate in communication theory at the University of Minnesota. He formed a company to market the Personal Profile System®, which became the DiSC.
To summarize, the RMP is the clear choice for clients who are seeking a scientifically developed and independently validated measure of what motivates people.