Unaided Categorical Psychodiagnosis is not Coherent with Normative Models
Normative models require the data to be linear. Each case should be weighted linearly and combined additively. That is certainly not the case in clinical settings. Not all therapists have clear guidelines for themselves on what to base a categorical decision. When comparing the data at hand they rely on statistical models that are fallible. They are subject to the same biases that “normal people” are subject to: They think that the information presented matches the diagnose even if the behaviour could be interpreted as ambiguous and that other people would consent with their diagnosis.