Early intervention to prevent psychosis requires first that there be an accurate tool to identify who will later become psychotic and who will not. Unfortunately, no such accurate tool exists. The false positive rate in selecting prepsychosis is at least about 60-70% in the very best of hands and may be as high as 90% in general practice. That’s right, folks, nine misidentified non patients for one accurately identified truly prepsychotic patient. Those are totally unacceptable odds.