logistic curve

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logistic curve

[lə′jis·tik ′kərv]
(statistics)
A type of growth curve, representing the size of a population y as a function of time t : y = k/ (1 + e -kbt ), where k and b are positive constants. Also known as Pearl-Reed curve.
More generally, a curve representing a function of the form y = k/ (1 + e cf (t)), where c is a constant and ƒ(t) is some function of time.
References in periodicals archive ?
The logistic function parameter [gamma] = 1, [alpha] = 0.17, and [beta] = -33, -27, -20, and -25 m for high speed, medium speed, low speed, and all-vehicle scenarios, respectively.
Table 3 presented the best results obtained regarding the fitting procedure (maximizing [R.sup.2] and minimizing MSE) attained with the Logistic Function (LF) model for all S/I ratio evaluated (See Figure 2).
(2012) reported that the Logistic function describes the data better, and Beiki et al.
For this reason, we had to assume that edentulism in Brazil follows the same logistic function that has been shown for other countries.
The [P.sub.th] and [P.sub.sat] were calculated from the 3rd derivative of the logistic function, and they were expressed as [P.sub.th] = [P.sub.3] (1.317/[P.sub.2]) and [P.sub.sat] = [P.sub.3] + (1.317/[P.sub.2]).
At the end of the analysis, a logistic function is proposed to create acceptance zones in the router.
All the above mentioned articles have ignored the cost of granting credit period to customers and none of them have assumed demand rate to be a logistic function of credit period.
The logistic function is the mathematic expression of the logistic growth law.
The logistic function illustrated in equation (3) is of the most common form.
As an example, two models for energy allocation were derived: a step-function and a logistic function. The extended model can jointly describe growth in adult and juvenile stages.
For the scenario where de-recruitment is not considers, the exploitation pattern is modelled by a logistic function:
the maximum likelihood extermination function can be used as follow to estimate the regression model of the logistic function [6].

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