Comment by tsoukase

Esp in mental health there is a large overlap of symptoms between diagnoses. So doctor's experience is needed to get the right diagnosis. No database and, hell, no AI assistance yet.

It all boils down on how deep a doctor goes diagnostically: for common diseases (1/100) an interview is enough, for rarer (1/1000) an MRI/blood test are needed and for very rare you need extensive and expensive genetic and immune exams. Because of cost, the 'art of diagnosis' is to be able to filter the cases that should be referred downward. Classic type I/II error due to binary misclassification happens all the time.