The Five-Factor Model

What it is

The model is measured by instruments including the Revised NEO Personality Inventory, and HEXACO is the live six-factor alternative, adding an honesty-humility dimension. Neither the model nor its instruments have a single originator, and none is claimed here.

The practical difference from a type instrument is easy to state. A type result tells you which of sixteen boxes you are in. A five-factor result tells you where you fall on a distribution for conscientiousness. The second can be a little higher next year without the first thing about you having changed identity, which is what makes the model usable by the literatures on personality change.

Its support includes replication of the five-factor structure across more than fifty countries, behaviour-genetic evidence, identifiable childhood antecedents and temporal stability across the lifespan. On outcomes, Brent Roberts, Nathan Kuncel, Rebecca Shiner, Avshalom Caspi and Lewis Goldberg found in 2007 that traits predict mortality, divorce and occupational attainment at magnitudes comparable to socioeconomic status and cognitive ability.

In effect

It is not beyond criticism, and the criticisms are real. The model is descriptive rather than explanatory: it tells you what varies without telling you why. It comes from lexical and factor-analytic methods with known indeterminacy in how many factors to extract. Its cross-cultural universality is stronger for the structure than for the meaning of the individual traits. HEXACO is a serious alternative rather than a fringe one.

Hold all of that and it still beats the type instruments on every psychometric axis, because it is measured on continua, has good test-retest reliability and carries a large criterion-validity literature. That is the comparison that matters whenever a workplace or a popular book is choosing between them.

The popular treatment in Benjamin Hardy's Personality Isn't Permanent is mostly to his credit on this point. At pages 30 to 31 he calls the model the most scientifically backed theory of personality, lists all five factors in plain language and insists explicitly that none of the five are types and that we sit on continua. That is correct, and it is the distinction most popular writing on personality tests fails to draw.

What it does not say

It does not put the research instruments in the same class as the type tests. At page 2 of that same book, NEO and HEXACO are listed among a single class of culprits alongside the Color Code, Myers-Briggs, DISC, Winslow, Birkman, the Enneagram and inkblots. They are the standard instruments of the trait literature the book relies on twenty-eight pages later. Flattening them into one category is convenient for the argument and is not defensible.

It does not licence profiles nobody administered. At pages 19 to 21 the same book gives a named climber full five-factor profiles for two years a decade apart. No test was administered. The hypothetical is signalled grammatically, in would score and would likely score, and the passage still functions as before-and-after data and reads as such. It is the clearest instance in that book of a story wearing the clothes of measurement.

It does not explain anybody. A position on five dimensions is a description of how a person's behaviour varies relative to other people's, and treating a score as a cause of what somebody did reverses the direction of the evidence.

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