There is no test that can make a schizophrenia diagnosis. People with schizophrenia usually come to the attention of a mental health professional after others see them acting strangely.
Doctors make a diagnosis through interviews with the patient as well as with friends and family members.
Psychiatrists have the most experience with diagnosing schizophrenia. A psychiatrist or other licensed mental health professional should be involved in making a schizophrenia diagnosis whenever possible.