The research method being used by Dr. Crane while diagnosing a patient who is going through the residual phase of schizophrenia is the case study method.
A case study method is one of the research methods used to identify the patient's detailed study about his/her respective illness.
According to a given situation, the interviews and interactions being taken by Dr. Crane with the patient in order to know well about his/her condition as he is going with the disease of schizophrenia. His colleague makes notes of whatever going through during those interviews and interactions. These notes helped him to analyze the case and then prescribe an appropriate solution for overcoming his/her illness.
Therefore, the case study method is being followed by Dr. Crane in order to diagnose the patient's illness of schizophrenia.
Learn more about the schizophrenia in the related link:
https://brainly.com/question/23035586
#SPJ1