ABSTRACT
Demographic, psychometric, and biological characteristics of the severely and mildly retarded children are presented in this chapter. Three levels of socioeconomic status (SES) derived from the socioeconomic index scores of the families at the 7-year follow-up (Nichols & Chen, 1981) were defined. SES I includes scores in the lowest quartile of the distribution in the total study population; SES II, scores in the middle 50%; and SES III, scores in the upper quartile.
