logistic curve


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lo·gis·tic curve

an S-shaped curve that depicts the growth of a population in an area of fixed limits.

logistic curve

an S-shaped curve of numbers against time that represents the growth in numbers of a population of organisms in a limited environment. see GROWTH CURVE.
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Learning from the above methods, this paper combines Logistic curve fitting and back propagation (BP) network learning algorithm to predict the potential of electric energy substitution.
rosacea [L.sub.50] for the coastal area of Santa Rosalia, BCS, estimated by adjusting a logistic curve, was 40.8 cm TL for both sexes combined, 37.3 cm TL for males, and 42.4 cm TL for females (Fig.
The thought that I've often used to guide myself in my postulated future histories is that human progress will probably be like many other phenomena, and eventually be describable by a logistic curve, in which a long period of slow improvement is followed by a period of rapid progress, followed by a leveling off to a slower rate of change, as various limits and difficulties arise to complicate further progress.
The difference equation (4) captures the continuous solution of the differential equation (3); that is, the solution shows the logistic curve [15].
Although some numerical values of the health index are different, for example, the health index value of number 3 transformer is 0.007 and its value given by fuzzy-logic method is 0.3, they are not contradictory since the proposed method for health index calculation is based on the logistic curve. It is a common outcome on the transformers' health index, whose health conditions are good or very good because the initial stage of logistic curve is tending to zero.
The dose-response curve of the calibrator hepcidin-25 was approximated by a 4-parameter logistic curve and showed a dynamic range (SD) of 21 (8) pmol/L to 3.1 (1.2) nmol/L (n = 24).
Applied to nonlinear models, the logistic curve models the sigmoid function, where growth is initially exponential models (increases by a constant percentage depending on time), and after certain time slows down (growth rate decreases) and finally, in maturity, stops.
The logistic curve developed for the relationship followed the actual proportions of individuals that were mature in 13 data bins based on the OL:OW ratio (Fig.
It can be noticed that if the market is stable, the shape of the index usually assumes the form of a logistic curve (Prescott, Hansen 2005; Ambler, Cardia, Zimmermann 2004; Comin, Gertler 2006).
wherein the i index represents the item; [a.sub.i] is denominated item discrimination parameter; [b.sub.i] is denominated item difficulty parameter, D is a scale factor, a constant and usually equals 1.7, used to approximate the logistic curve to the normal distribution, the higher [a.sub.i] parameter's value, the more sensitive the model becomes against the variations around its difficulty point, therefore it is known as item discrimination parameter.