Don Riso and Russ Hudson have been vigorous in discerning accuracy and verifiability for their Enneagram typology.
The Enneagram Institute supports anyone who wishes to embark on research in any way they can. This usually takes the form of inviting the many thousands of Riso-Hudson students to participate in a research project.
The following are brief outlines of recent research projects undertaken by independent researchers. The full results can be viewed on the Enneagram Institute original website that is available to view still, thanks to the "WayBack Machine" Internet Archive: https://web.archive.org/web/20060101064835/http://www.enneagraminstitute.com/research.asp
Sara Scott’s Doctoral Dissertation Research
Sara Scott, a Doctoral Candidate in Counsellor Education at the College of William and Mary in Virginia, has defended her dissertation, which has produced the first and only empirical evidence of nine personality types as proposed by the Enneagram typology!
Scott used a statistical method called Factor Analysis to analyze the data. She took the statements from our main personality typing instrument, the RHETI (Riso-Hudson Enneagram Type Indicator) as a starting place. Some of the RHETI items were re-worked to conform to the standards of clarity and simplicity for the design of scale instruments, and all were rearranged in a 6-point agree/disagree Likert-scale format. Then using Factor Analysis, she analyzed all the responses to each item in different ways to show which items correlate most strongly with each other. The idea is that a response to one of the items in a cluster predicts responses to other items in that same cluster as well, with the hypothesis that nine different personality clusters (factors) will form.
Data from 6401 subjects were collected with the instrument. The data were split in half to allow validation of the results of factor analysis of the first half of the dataset by application of the refined factor solution to the second half of the dataset. The data, collected from a broad demographic, factored into nine distinct factors, each of which was a clear description of one of the nine Enneagram personality types as they are described in popular literature about the Enneagram.
Values of Cronbach’s coefficient alpha for each of the factors established that each was an internally consistent measure. Internal consistency of the factors was not affected by whether or not subjects had prior knowledge of their Enneagram types, nor by their gender. The refined factors were validated by descriptive statistics which showed that subjects scored highest on the items of the factor which was descriptive of the same Enneagram type that those same subjects identified as their types. These results from the first half of the dataset were upheld with the second half, providing strong support for the Enneagram typology.
This dissertation offers empirical evidence that the Enneagram is a validated personality typing system—that there are, indeed, nine different types of meaning-making, nine different types of people in the world, as represented by the nine personality types.
2005: SHL’s Preliminary Research
SHL (UK) is the world's leader in occupational testing. In 2004, Don Riso and Russ Hudson were invited by SHL to embark on a major research project to explore the connections between SHL’s trait-based psychological tests and the Enneagram system. The Riso-Hudson interpretation was chosen by SHL because it is clear, complete, and specific enough to be scientifically testable.
After a year of testing, independent researchers at SHL, lead by Prof. David Bartram, found that the nine personality types of the Enneagram are "real and objective," and that they stand on a par psychometrically with the Myers-Briggs system, the Big Five, and other well-known, accepted psychological systems.
In short, the Enneagram is now "scientifically supported" by preliminary tests, and two more years of research are being planned to further validate the Enneagram scientifically.