A retrospective study is set up to examine the risk factors for parenting a mentally retarded child. The parents of all children with mental retardation in a given region all agree to cooperate in answering an extensive questionaire covering a large range of factors that could possibly be relevant to mental retardation. Neigh-bors of the families with retarded children are given the same questionaire. If the nearest neighbor is not prepared to cooperate and/or has no children, the questionaire is given to the nearest neighbor who will cooperate and has children.

Would this study be capable of detecting the following possible causes of mental retardation?

a. Mother suffering from rubella (German measles) in pregnancy.

b. Parents having many children.

c. Age of parents.

d. Mother suffering from poverty and malnutrition.

e. Residence near a lead smelter. P-963