My 10 year old son and I watched an interesting show on the science channel yesterday called Searching for Sanity where a group of experts in psychiatry and psychology tried to figure out who, among a group of ordinary looking people, some of whom had diagnosed disorders and some perfectly normal, had certain psychiatric disorders. The experts were not told anything about their backgrounds. Social anxiety, bipolar, and depression were some of disorders they were looking for and they could only watch for clues in their behavior in order to match people with disorders. The experts got it wrong more than half the time. The show made it easy to see how misdiagnosis could occur. Some of the people they suspected of having a psychiatric disorder were perfectly normal.
This is true in most every Field. Most "experts" have a working knowledge of their field, but no formal process for evaluating their subjects, separating possible causes, then reevaluating their diagnosis as they gain more information. Many more will throw the process out when faced with novel situations.
