Introduction

This chapter deals with measuring growth using primarily anthropometric techniques and external dimensions of the body such as height, weight and measures of subcutaneous fat. Of course, there are situations in which changes in various components of body composition are also valid measures of growth and in these situations non-invasive anthropometry will not be the method of choice. Chapter 6 discusses these techniques in detail.

Our knowledge of the process of human growth and development is directly dependent on the methods employed to measure that process and the scientific and/or clinical context within which those methods are employed. The methods concern not only the instrumentation and measurement technique but also the frequency of assessments. Daily assessments will lead to a different model of the growth process than weekly, monthly, quarterly or yearly assessments (Lampl et al., 1992). Clearly the accuracy and reliability with which we can measure will play a major role in determining the frequency because too short a period of time between assessments may mean that any apparent change is due to error rather than to growth.

The context will usually be one of three types: screening, surveillance or monitoring. Screening is concerned with the identification of a particular subset of the population with certain prescribed characteristics. Most usually they will be outside (above or below) a certain cut-off point for height, weight, or a combination of the two such as weight-for-height or body mass index (BMI).