Cluster Analysis of the Klein Sexual Orientation Grid in Clinical and Nonclinical Samples: When Bisexuality Is Not Bisexuality

A cluster analysis of the Klein Sexual Orientation Grid (KSOG) in three samples (Internet-recruited men and women; HIV study men) resulted in objectively determined 4- or 5-cluster classifications (such as “bi-heterosexual” or “bi-bisexual”). Group means and standard deviations on the KSOG's 21 items revealed that overtly erotic items (sexual fantasies, sexual behavior, sexual attraction) and self-identification items were more uniform within groups than social items (emotional preference, socialize with, lifestyle) were. The bisexual cluster in the HIV sample was distinctly different from all of the bisexual main sample clusters. Attempts to generalize from this clinical bisexual group to a larger population would be doomed to failure. This underscores the importance of recruiting nonclinical samples if one wants insight into the nature of bisexuality in the population at large. Our data empirically confirm many previous nonempirical warnings against clinical samples in studies of sexual orientation.