CONCLUSIONS

The generalised logistic and Gompertz functions provide a flexible family of curves for summarising and comparing growth.
The estimated parameters can be used to study differences in growth patterns in different population treatment groups.

The formula for the generalised logistic takes the form :

Y = A + C/(1 + T exp(-B(x-M))) ^ (1/T))

where

Y = weight, height, size, etc... and
X = time

The parameters of the generalised logistic have the following roles:

A - controls the lower asymptote;
C - controls the upper asymptote;
M - controls the time of maximum growth;
B - controls the growth rate;
T - controls where the maximum growth occurs.

The Gompertz function can be regarded as a special case of the generalised logistic when the parameter T is close to zero or very large.

CONCLUSIONS

Growth curve modelling 1.6.95 Page : 11 of 12