High power polynomial regression for the study of distance, velocity and acceleration of growth.

A technique is given to use high power polynomials of logarithms of age, up to order 18, to describe, as exactly as possible with the given data, the growth as such, the growth velocity and acceleration of any desired parameter in function of age. E.g., this can be done for height or weight in children and for blood pressure or serum cholesterol or serum uric acid a.s.o. in children and adults. The growth velocity and acceleration are given at any age between the observation limits, in a dimensionless and in a linear form. Although the linear velocity id clinically more easy to understand, the dimensionless growth velocity has many advantages. Among them, it makes it possible to compare, e.g., the growth of weight and height or of blood pressure and serum cholesterol in the same individual or in the same population at a given age or it permits the comparison between individuals, between different populations or within the same population, but at different ages, of the same parameter (e.g., height, serum cholesterol a.s.o.). The comparison of growth velocity between different species is also preferably done with the dimensionless growth velocity.