Self-injurious and stereotypic behavior of noninstitutionalized mentally retarded people: prevalence and classification.

A nationwide mail survey on self-injurious behavior (SIB) and stereotypies was carried out among noninstitutionalized mentally retarded people in the Federal Republic of Germany. The estimated SIB prevalence among 25,872 retarded persons from 294 service facilities was 1.7%, which is considerably lower than earlier estimates based on samples of institutionalized persons. Prevalence of stereotypic behavior among individuals with SIB was 65%, compared to 62% in a control sample of persons without SIB. A cluster analysis distinguished three SIB clusters. Different types of stereotypic behavior were found to be differentially related to different types of SIB.