Abstract
Although the notion of growth coefficient is important in growth analysis, its meaning is not necessarily pointed out clearly, at least analytically. The present paper, based on the von Bertalanffy model, gives an extended quantity of it and investigates its properties for logistic and Gompertz models. It is age dependent and converges to the coefficient of age in the models, growth coefficient in the traditional sense. The graphs of the quantity and the length show similarity for the logistic model, but not for the Gompertz model, although they show the same type of fluctuation. Moreover, the analysis indicates that the newly defined quantity has a property suitable to be called a growth density of the growth of length. Our discussion also shows the importance of the notion of growth remainder.
