Personality tests, are they BS?

[LeftishBrit]

1. Not all, and not completely; though I would be cautious in using them as a main method of assessment

The 'Big Five' test of Costa and McCrae, and Eysenck's Personality Inventory, have been evaluated and found to be at least reliable (i.e. give similar results for the same person at different times, and when scored by different people). They are valid (i.e. actually measure some of the things they're supposed to) to some degree: e.g. there are some consistent differences between people high and low on extraversion, or on neuroticism, both on behavioural and some physiological measures. I would not advise using even these tests as the main measure for diagnosing people, or assessing them for jobs, however.

The Myers-Briggs, though frequently used, has not been found to be even particularly reliable, let alone valid. Also, it is based on an outmoded attitude to personality: that it can be classified into distinct 'types'. In fact, the evidence is that personality characteristics vary more according to continuous dimensions ('traits'). For example, extraversion varies continously, with some people being at one extreme or the other, and most being at various points in between, rather than people being either introverts or extraverts.