It was assumed that the sampling procedure was purely random with respect to the personality variables under investigation.

An interview schedule of open-ended questions and a multiple-choice questionnaire were prepared, and one parent of each of the sample children was seen in the home. The parent was asked to describe the child's typical behavior in certain standard situations in which there was an opportunity to observe tendencies toward perfectionism in demands upon self and others, irrational conformity to rules, orderliness, punctuality, and need for certainty. The interviewers were instructed not to suggest answers and, as much as possible, to record the parents' actual words as they described the child's behavior in home situations.

The rating scale of compulsivity was constructed by first perusing the interview records, categorizing all evidence related to compulsivity, then arranging a distribution of such information apart from the case records. Final ratings were made on the basis of a point system which was developed after studying the distributions of actual behaviors recorded and assigning weight values to each type of behavior that was deviant from the discovered norms. Children scoring high in compulsivity were those who gave evidence of tension or emotionality in situations where there was lack of organization or conformity to standards and expectations, or who made exaggerated efforts to achieve these goals. The low compulsive child was one who appeared relatively unconcerned about such matters. For instance, the following statement was rated low in compulsivity, ``She's naturally quite neat about things, but it doesn't bother her at all if her room gets messy. But she cleans it up very well when I remind her.''