As with the von Bertalanffy model, a lack of smaller animals in the juvenile stages was the weakest scenario for fitting a Gompertz curve
The Gompertz curve
has the following mathematical formulation:
The Gompertz curve predicted initial exponential growth, starting from very small increments for the smallest abalone and reaching a maximum and tailing off as initial length increases.
The ven Bertalanffy curve predicts very rapid early growth and so, all other things being equal, would predict the highest productivity levels, whereas the Gompertz curve predicts very slow early growth and thus would predict the lowest productivity.
An S-shaped Gompertz curve (33)--in which the decrease is slow initially, accelerates, and slows down again, trending to a stable level--best illustrates the past trends in H.
pylori transmissibility and found that a Gompertz curve best fits the past trends of H.
The parsimonious representation provided by the Gompertz curve
is particularly important for the annuity calculations below.
The approach here is to fit a Gompertz curve
to market share using an economic variable to modify market penetration.
For this forecast model, an estimate of cellular subscribers through 2010, using the Gompertz curve
, is taken.
Adjusting the base of the Gompertz curve
(rightmost curve in, Richards, Fig.
The observed growth curves and the Gompertz curves
fitted for each genotype are shown in Figure 2.
Mean size-at-age values for each region were then fitted with seasonalized von Bertalanffy and Gompertz curves
, as described previously.