premise: Dissociative identity disorder is known only in the United States of America.
hypothesis: Dissociative identity disorder ( DID ) , also known as multiple personality disorder ( MPD ) , is a mental disorder characterized by at least two distinct and relatively enduring identities or dissociated personality states . It is believed to affect between 1 % and 3 % of the general population , and between 1 % and 5 % in inpatient groups in Europe and North America .