M questions face researchers conducting personality disorder research. Which measure should be used? When should patients be evaluated—at initial presentation when they are still symptomatic, or after symptom resolution? Can a patient accurately describe his or her personality, or must an informant be contacted? What do you do when personality traits change during an individual's lifetime? I discuss these and other issues of personality disorder assessment in the DSM-III/DSM-III-R era, and examine the empiric literature bearing on these questions. First, I review studies of diagnostic reliability and stability, because studies of the above questions can only be interpreted in the context of the limitations imposed by modest reliability.
Zimmerman M. Diagnosing Personality DisordersA Review of Issues and Research Methods. Arch Gen Psychiatry. 1994;51(3):225-245. doi:10.1001/archpsyc.1994.03950030061006