AN ESTIMATE OF THE DURATION OF THE LAG PHASE OF THE LOGISTIC GROWTH CURVE

Abstract

The duration of the lag phase of growth (λ) has been estimated from the logistic function (y) in at least three ways. While they differ substantially from one another, none of them is particularly stringent. The central estimate of λ is based on the point at which the curvature (κ) of y is maximal. Unfortunately, the expression given for this estimate is based on the assumption that κ can be approximated by the second derivative of y. This is equivalent to assuming that the rate of growth is zero, leading to relatively large values of λ. Avoiding this assumption yields a simple expression for a more stringent estimate of λ. The new estimate might be of particular value when only very limited growth can be tolerated.