Traits vary continuously between people; a type is a line drawn across that continuum, and everyone near the line is misdescribed.
Why it matters when the plan changes
Types are attractive for exactly the reasons they are weak as evidence. Four letters or a colour are easy to remember and repeat, and a team can talk about itself in that language within an hour. The cost is that two people with nearly identical scores can receive different labels, and two people with the same label can be very different, which is the opposite of what a decision needs. People differ along continuous dimensions that stay relatively stable over time, and a category cuts that continuum arbitrarily.
The tension is that type language is genuinely useful for conversation and genuinely unsuitable for decisions. Used to open a discussion about how a team works, it does little harm. Used to inform who gets a role, it converts a measurement into a caricature and acts on the caricature instead. The modern model describes five broad continuous dimensions rather than discrete boxes. Many organisations do the second while believing they are doing the first.
In practice
A leadership team runs a typing workshop and each member receives a label. The labels become shorthand in meetings and, gradually, in decisions: one member is passed over for a role because their type is thought unsuited to it. The underlying scores put them a fraction from the boundary of a type considered ideal. The label did the deciding.
Evidence
Traits differ across individuals along continuous dimensions and are relatively consistent across situations, which a categorical type cannot represent.
Trait theory, Wikipedia (2026)The dominant modern model of personality describes five broad continuous dimensions rather than discrete types.
Big Five personality traits, Wikipedia (2026)
What it cannot tell you
A type-based assessment cannot tell you how far a person sits from the boundary between categories, only which side they fall on. It is silent on the size of a difference between two people placed in the same category, and it cannot distinguish someone barely inside a type from someone firmly within it.
Questions
Because a label is easy to remember, easy to share and easy to build a workshop around. A team can discuss itself in type language within an hour, and the language feels insightful. Those are real benefits for conversation. They are not properties that make a measure suitable for decisions.
Most attributes vary continuously, so a type is a cut across a distribution. As Trait theory (Wikipedia, 2026) describes, traits are relatively stable over time and differ across individuals along continuous dimensions, not fixed boxes. People near the cut are assigned arbitrarily and can change type on retest, discarding the information a decision needs.
As a way to open a conversation about how a team works, with the understanding that it is a simplification, it does little harm. As an input to a decision about a person's role or advancement, it is unsuitable, because it acts on a caricature of a measurement rather than the measurement.
It keeps the score. Rather than sorting people into boxes, a trait approach places each person on a set of dimensions, much as the Big Five personality traits model describes five broad continuous dimensions rather than discrete types. That keeps the information a decision needs, even though it is less memorable than a label.
How stable the type assignment is on retest, what evidence links type to any outcome the buyer cares about, how people near a boundary are handled, and whether the supplier recommends the tool for decisions or only for discussion. The answers usually settle the question.