

A small number of trained researchers were able to get an insight into sexual behaviour in the American population using the scale, but comparing different studies using the Kinsey scale becomes difficult. It is also the interviewer who has to define whether the subjects gave honest answers or when to ask further questions. Depending on the behaviour and reactions of the interviewer, subjects may or not be willing to disclose their full sexual history. The assessment involves the subjective rating of the interviewer. However, the Kinsey scale also has some shortcomings.

In his reports Kinsey showed the big variance in sexual orientation in the American population and claimed that homosexual encounters and fantasies were much more common than previously believed. Before Kinsey, sexual orientation was conceptualized as only three categories: homosexual, heterosexual and bisexual, and homosexual contacts were regarded as rather rare. The Kinsey Reports and the developed scale had a big impact on the perception of human sexuality in general and homosexuality and bisexuality in particular. In the interview, it was assumed that participants had tried different kinds of sexual acts, until explicitly negated. The wording was also not rigidly fixed, but could be adapted to e.g. Depending on the subject's answers there could be a different order and number of questions. This interview included around 300-500 questions. Subject sexual orientation was assessed in a structured personal interview. Predominantly homosexual/only incidentally heterosexual Predominantly homosexual but more than incidentally heterosexual Predominantly heterosexual but more than incidentally homosexual Predominantly heterosexual/incidentally homosexual The measurement for sexual behaviour was relative to the subject's full number of sexual encounters, rather than an absolute number of sexual encounters with the same sex. Equal intervals were assumed between the single categories, except for X.

Kinsey used 7 categories (0-6) to classify sexual orientation as a continuum plus an additional category labeled X (no socio-sexual contacts or reactions). It assesses both overt sexual behaviour as well as sexual fantasies. The scale was used to classify and quantify homosexual and heterosexual behaviour across the American population. The two books are often referred to as "the Kinsey Reports". The Kinsey scale (also Kinsey homosexual-heterosexual scale) was first presented by Alfred Kinsey in his two influential books Sexual Behavior in the Human Male (1948) and Sexual Behaviour in the Human Female (1953).
