Certain technical aspects of longitudinal studies of child health and development.

Abstract

THE title Child Health and was originally chosen for this project to indicate its primary purpose, that of obtaining as much information as possible about the interrelationships between and development. Since this project was started 19 years ago, the term health has been interpreted broadly to include mental, emotional, and physical fitness as well as the incidence of illnesses and the presence of handicapping conditions. Attention has been given to these aspects at succeeding ages, as well as to the diet and certain features of the environment, care, and management of the child. Development likewise has been thought of as encompassing all aspects of progress in growth and maturation. Attention has always been given to physical, physiologic, and psychologic factors insofar as opportunity has permitted. The objective which has constantly guided the planning and execution of this project has been to understand as fully as possible the basic attributes of each individual, the characteristics of his progress in growth and development from birth to maturity, and the influence of and environment at successive stages upon this progress and upon his ultimate development. It is hoped that better concepts of the importance of constitutional differences between children will emerge from these studies as well as a clearer understanding of what constitutes satisfactory progress for several essentially different types of children. Better means are sought for recognizing at successive stages what features of growth and development are significant in respect to the ultimate attainment of and fitness. It is also hoped that light will be thrown upon the different needs of constitutionally different children. Certain limitations in the possibilities for acquiring the desired information and for drawing conclusions from the data obtained from repeated studies of one sample of children were recognized from the beginning and others became more apparent with experience. To mention a few: (1) When many aspects of and development are being investigated on the same individual, all cannot be thoroughly studied; (2) the same investigator cannot be counted on to obtain any given information throughout the span of such a study, and any one investigator will change with the years as do his subjects; (3) some aspects of the health, care, and development of children are far more readily investigated than others; (4) some information is obtainable but is highly subjective in