The Assessment of Growth and Development in Children

Standards of growth in current use employ either the percentile division outlined above or else a division of the healthy population by standard deviations* (e.g. Sontag and Revnolds, 1945). In * The standard deviation (a) is a measure of the spread of a frequency distribution. It is particularly appropriate to Gaussian distributions, in which the correspondence of various multiples of a to various percentiles can be seen from Figs. IA and lB. It is estimated from a sample of readings as the square root of the sum of the squares of the desiations of the readings from their mean divided by one less than the number of readings.