Notes
1. The data reported here were collected as part of a program “Verbal Enrichment and School Achievement in Lower Socio-economic Groups”, which is supported in part by a grant from the Taconic Foundation and is part of a program for “Cognitive and Motivational Development of the Scholastically Retarded Child”, supported by Research Grant No. MH-820 from the National Institute of Mental Health of the National Institutes of Health, Public Health Service.
2. The writers wish to acknowledge the help of Dr. Martin Whiteman with the many statistical problems encountered in the course of this study.