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Topic: Generalised logistic curve


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In the News (Mon 7 Dec 09)

  
  Logistic function - Wikipedia, the free encyclopedia
The logistic function or logistic curve models the S-curve of growth of some set P. The initial stage of growth is approximately exponential; then, as competition arises, the growth slows, and at maturity, growth stops.
The logistic function is the inverse of the natural logit function and so can be used to convert the logarithm of odds into a probability; the conversion from the log-likelihood ratio of two alternatives also takes the form of a sigmoid curve.
Verhulst derived his equation logistique (logistic equation) to describe the self-limiting growth of a biological population.
en.wikipedia.org /wiki/Logistic_curve   (741 words)

  
 Logistic function -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-29)
These functions are found in a range of fields, from (The science that studies living organisms) biology to (The branch of social science that deals with the production and distribution and consumption of goods and services and their management) economics.
The sigmoid curve shows early (additional info and facts about exponential growth) exponential growth for negative t, which slows to linear growth of slope 1/4 near t = 0, then approaches y = 1 with an exponentially decaying gap.
Verhulst derived his equation logistique (logistic equation) to describe the self-limiting growth of a (additional info and facts about biological) biological population.
www.absoluteastronomy.com /encyclopedia/l/lo/logistic_function.htm   (629 words)

  
 Logistic function - Open Encyclopedia   (Site not responding. Last check: 2007-10-29)
A typical application of the logistic equation is a common model of population growth states that:
This function is also called the standard logistic function and is often encountered in many technical domains, especially probability, statistics, biomathematics, and economics.
Equation (1) is the continuous version of the logistic map.
open-encyclopedia.com /Logistic_curve   (388 words)

  
 Logistic Curve   (Site not responding. Last check: 2007-10-29)
The logistic curve is used to model a variety of physical situations in which a In situations of "controlled growth" the logistic curve frequently
Other descriptions of Logistic curve The logistic function or logistic curve is defined by the mathematical formula: for real parameters a, m, n, and t.
Other descriptions of Generalised logistic curve The generalised logistic (or Richards') curve is a widely used and flexible function for growth modelling.
www.simonsonlyhere81.info /logistic-curve.html   (535 words)

  
 iqexpand.com   (Site not responding. Last check: 2007-10-29)
The logistic equation (sometimes called the Verhulst model or logistic growth curve) is a model of...
Derivative of the Sigmoid Function or Logistic Function or Activation Function /// The derivative of the Logistic Activation Function is represented with /// F(x) = F(x)*(1- F(x)) where F(x) is...
Analyzing the Spread of SARS with the Logistic Function From: John Conover andlt; john@email.johncon.com andgt; Subject: Analyzing the Spread of SARS with the Logistic Function Date: 22 Apr 2003 08:39:21 -0000 Note...
logistic_function.iqexpand.com   (684 words)

  
 logistic curve
The sigmoid curve is the curve whose formula is the sigmoid function
Members of the family of curves with obtained by linear scaling and translation of the sigmoid curve are called logistic curves, and are found in a range of fields, from biology to economics.
The logistic curve is used to model a variety of physical situations in...
www.fact-library.com /logistic_curve.html   (218 words)

  
 Logistic function - TheBestLinks.com - Biology, Differential equation, Economics, Logistic map, ...   (Site not responding. Last check: 2007-10-29)
Logistic function, Biology, Differential equation, Economics, Logistic map...
The sigmoid function or sigmoid curve is a special case of the logistic function (for parameters a=1, m=0, n=1, \tau=1 ):
See also sigmoid curve, for related uses of this term.
www.thebestlinks.com /Logistic_function.html   (511 words)

  
 GROWTH CURVE MODELLING - Smart Module
The Gompertz curve is a limiting case of the generalised logistic as T becomes very small or very large.
A further example is available which illustrates the fitting of separate growth curves for each experimental unit.
The data and the Genstat code, which fits growth curves for each experimental unit and forms a table of the medians for each of the five parameters of the Gompertz curve, is provided here.
www.bioss.ac.uk /smart/unix/mgrow/slides/frames.htm   (770 words)

  
 Curve Generalised Logistics   (Site not responding. Last check: 2007-10-29)
For each mode/route alternative the generalised cost is calculated by The inspection of the learning curve regarding the alternatives is also important.
In the curve drawn, the points made are all too generalised.
It plots a deterrence curve that was calibrated during one of the case studies
www.sic68.info /curve-generalised-logistics.html   (675 words)

  
 Logistic function - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-10-29)
The terms logistic function and logistic curve mean either the standard sigmoid function, or any function obtained from it by linear scaling and translation; that is:
The solution to this equation is a logistic function.
The logistic function is the inverse of the logit function and so can be used to convert the logarithm of odds into a probability; the conversion from the log-likelihood ratio of two alternatives also takes the form of a sigmoid curve.
www.encyclopedia-online.info /Sigmoidal   (299 words)

  
 Regression Using R
The basic regression command in R is GLM (general, or generalised, linear model).
The second reason to bother with this is that, although R has a steep learning curve to start with, it gets flatter, faster, than other programs, because all of the commands are very similar.
Multilevel models in R are similar: instead of the glm() command, we use the lme() command (for linear mixed effects) or nlme() for non-linear mixed effects.
www.jeremymiles.co.uk /regressionbook/extras/appendix2/R   (1405 words)

  
 Properties of Some Generalised Logistic Maps with Fractional Exponents
In contra-distinction to the customary logistic map, for the case of generalised unimodal maps with derivative equal to zero at the origin, the attractor may depend on the initial x value, and the map iterates to zero if this x is too low or too high.
For the largest stable periodic points, it is the tangent to their curves.
The generalised map (2) with a > 1 exhibits many features which are quite different from the standard logistic map (1) (a=b=1).
journal-ci.csse.monash.edu.au /ci/vol02/gottlieb/gottlieb.html   (1701 words)

  
 Paper 98/5 Lupins extn
By fitting logistic functions to curves which plotted the area planted to hybrid corn over time in different states of the U.S., he was able to estimate parameters which described the start time, rate and ceiling level of the adoption process.
A standard logistic function, Gompertz function and Richards function were fitted to the data for individual shires (see Appendix 1), giving estimates of the ceiling level of adoption attained, the intrinsic rate of adoption, and the time at which the maximum rate (i.e.
This function describes an asymmetrical curve that reaches its maximum rate of adoption earlier in the diffusion process, when approximately 37% of the final ceiling level is reached (or in this case when the percent of farmers adopting is A + C/e).
www.general.uwa.edu.au /u/dpannell/dpap985f.htm   (7361 words)

  
 SAS | Local Forum 2005   (Site not responding. Last check: 2007-10-29)
Logistic regression occupies a central position in the field of credit scoring as it is relatively well understood and an explicit formula can be derived on which credit decisions may be based.
Although artificial neural networks may be more powerful than logistic regression, it is not widely used in credit scoring because it is a fl box with respect to interpretation and the absence of reasons why the neural network has reached its decisions may be unacceptable.
Partial residuals are used to investigate the effect of the individual inputs, adjusted for the effect of the other inputs, where the jth partial residual is the deviation between the actual values and that portion of the fitted model that does not involve variable xj.
www.sas.com /offices/africa/southafrica/events/Local_Forum_2005/abstracts.html   (4080 words)

  
 REGIONAL FLOOD FREQUENCY ANALYSIS   (Site not responding. Last check: 2007-10-29)
Tables 1 and 2 show that the generalised extreme value, generalised Pareto and lognormal distributions are acceptable, according to the Hosking and Wallis (1993, 1997) goodness-of-fit measure, in most of the regions in hydro-ecoregion2.
The lognormal distribution used by Smith (1992), the generalised extreme value, the lognormal as well as the generalised logistic are acceptable in all the regions in hydro-ecoregion3.
The fitted distributions are the generalised extreme-value, the generalised logistic and the Wakeby (in bold).
intelligence.jrc.cec.eu.int /poplar/public/iain/floods/regional.html   (1959 words)

  
 HESS - Abstract   (Site not responding. Last check: 2007-10-29)
The accuracy of the asymptotic approximations for many of these intermediate results and for the quantile estimates was investigated by comparing the approximations to the outcome of a series of Monte Carlo experiments.
An investigation into the contribution of different components to the total uncertainty showed that for large returns periods, the variance of the growth curve is larger than the contribution of the median.
Therefore, statistical methods using regional information to estimate the growth curve should be considered when estimating design events at large return periods.
www.copernicus.org /site/EGU/hess/8/2/183.htm?FrameEngine=false   (259 words)

  
 [No title]   (Site not responding. Last check: 2007-10-29)
If you have Java enabled on this browser, you can experiment with various settings of the parameters of a generalized logistic curve and see the results plotted in the diagram below.
For comparison purposes the curve for the previous setting of the parameter is plotted in red while the current setting is in blue.
You can investigate the Gompertz curve by setting the T parameter in the Generalised Logistic to 0.5 first and then to 90.
www.bioss.sari.ac.uk /smart/unix/mgrow/slides/slide02a.htm   (85 words)

  
 Curve Generalised Logistics   (Site not responding. Last check: 2007-10-29)
...The terms logistic function and logistic curve mean either the standard sigmoid function.....The base civil engineering logistics function base civil engineering (SuDoc D 301.35:85-61.....Logistics & Fulfillment for E-Business : A Practical Guide to Mastering Back Office..
The generalised logistic (or Richard's) curve is a widely used and flexible function for..
...This mapping between a parabolic curve and a physical contradiction is complementary to.....Moving Beyond Trade-Offs’, International Journal of Physical Distribution and Logistics.....generalised ‘operator’ of the problem statements and in some cases covers similar ground..
www.justlogistics.info /resources/curve-generalised-logistics.php   (264 words)

  
  Lexicon of Statistical Modelling
The value of Z indicates the height of the ordinate of a continuous curve, and it represents the density of the items (density means the relative concentration of variates at a distance of Y from µ).
Logistic regression can therefore be used to obtain odds for the hypothesis that the likelihood of failure, or occurrence, is dependent on the treatment (which can have more than two levels, or be continuous).
The curve of the Poisson series is described completely by one parameter, as the variance is equal to the mean.
www.geodata.soton.ac.uk /biology/lexstats.html   (13070 words)

  
 Search Results for equation*
Petrovsky's main mathematical work was on the theory of partial differential equations, the topology of algebraic curves and surfaces, and probability.
He generalised Monge's idea of the characteristic of a partial differential equation from 2nd order equations to nth order equations.
In 1786 Bring reduced a general quintic to x5 + px + q = 0 while Jerrard generalised this to show that a transformation could be applied to an equation of degree n to remove the terms in xn-1, xn-2 and xn-3.
www-groups.dcs.st-and.ac.uk /~history/Search/historysearch.cgi?SUGGESTION=equation*&CONTEXT=1   (16630 words)

  
 Enter Main Keyword - Curve Generalised Logistics   (Site not responding. Last check: 2007-10-29)
curve generalised logistics generalised anxiety disorder generalised grammar phrase structure...
The curve must then be expressed.....in Management Sciences and logistics, the company now provides a.....flexibility.
The Installation, Hook Up & Commissioning (IHUC) Materials and Logistics Supervisor (M&LS) is responsible for the provision of services to the HUC Manager and the T&I Manager on a shared basis, while reporting to the HUC Manager.
www.logisticsrelated.com /directory/curve-generalised-logistics.html   (645 words)

  
 Ilya Nemenman's Digital Library   (Site not responding. Last check: 2007-10-29)
We find that an even better approximation, however, is to describe the relevant subspace as two dimensional, but curved: in this way we can capture 90% of the mutual information even at high time resolution.
Further, I don't quite understand how MI is calculated for "curved" features.
The co-information lattice sheds light on the problem of approximating a joint density with a set of marginal densities, though as usual we run into the partition function.
www.menem.com /~ilya/digital_library/full.html   (14952 words)

  
 London Metropolitan University » Module Catalogue » AC3026   (Site not responding. Last check: 2007-10-29)
This module provides an introduction to the statistical methods used in research in many areas, including business and accountancy.
The module covers the basic principles for the design of statistical investigations; multiple regression, analysis of variance and logistic regression.
Logistic regression: binary variables; binomial distribution; logistic curve; log-odds; generalised linear models; maximum likelihood.
www.londonmet.ac.uk /module-catalogue/3/ac/ac3026.cfm   (269 words)

  
 FACTORS AFFECTING THE GROWTH OF SACCHAROMYCES CEREVISIAE IN BATCH CULTURE AND IN SOLID SATE FERMENTATION   (Site not responding. Last check: 2007-10-29)
Cell dry weight (CDW) was calculated from a calibration curve.
The influence of this variable on the five key fermentation variables (biomass concentration, as grams of cell dry weight/l of medium), dead cells, total sugars and nitrogen and pH evolution) is summarised in Figure 1.
The cell growth curves were smoothed by a generalised logistic equation [19]:
ejeafche.uvigo.es /2(5)2003/001252003F.htm   (3417 words)

  
 Effective Computation of 2D Coupled Map Lattices
About the site function, instead of taking the logistic map which has been extensively studied either in chains [5] or in arrays (e.g.
In [19], Roy and Amritkar define a structure as a region of space such that the difference in the values of close sites within this region is less than a given threshold.
As such a simple definition could not be consistent with more advanced sophisticated structural models, we define a structure to be the curve on which the Laplacian of the image is zero.
pandora.nla.gov.au /pan/10178/20010710/www.csu.edu.au/ci/vol06/blanc-talon/blanc-talon.html   (3052 words)

  
 rg
Their major concern at the time was the search for counter examples in theories of continuous functions.
The early efforts were motivated by the search for space filling curves or conversely, well behaved 'perfect sets'.
What physicists did was to go and take straight limits giving things like the bell curve much loved by certain statisticians and social scientists.
d4maths.lowtech.org /rg.htm   (8586 words)

  
 Open Directory - Computers: Programming: Languages: Fortran: Source Code: Statistics and Econometrics   (Site not responding. Last check: 2007-10-29)
Adaptive Logistic Basis Function Regression (ALB) - Fortran 77 code by Peter M. Hooper.
Fortran Library - Fortran 90 program by Johnny Lin to calculate the time-dependent exponent (lambda) and logarithmic displacement curves of a time series.
ODRPACK: Software for Orthogonal Distance Regression - Solves the Orthogonal Distance Regresson (ODR) problem, that is, to find parameter estimates that minimize the sum of the squares of the weighted orthogonal distances between each observed data point and the curve described by a nonlinear equation.
dmoz.org /Computers/Programming/Languages/Fortran/Source_Code/Statistics_and_Econometrics   (2931 words)

  
 Spectral Signal Processing for ASR - Hunt (ResearchIndex)
Some variations and extensions of the standard analysis --- PLP, cepstrum correlation methods, LDA, and variants on log...
PLP applies the equal loudness curve and the intensity loudness power law to better exploit knowledge about the auditory system
1 Generalised Cepstral Analysis for Speech Recognition in Nois..
citeseer.ist.psu.edu /hunt99spectral.html   (743 words)

  
 piracetam1999-2000.html   (Site not responding. Last check: 2007-10-29)
Levetiracetam offers an effective and broad spectrum treatment of epileptic seizures, partial as well as generalised epilepsy.
Levetiracetam has been shown to be effective in genetic and kindled animal models of epilepsy and against chemoconvulsant-induced partial epileptic seizures.
The calibration curves were linear from 1 microM to 2 mM for plasma samples and from 0.5 mM to 38 mM for urine samples.
www.opt.indiana.edu /pietschwebmisc/piracetam1999-2000.html   (10059 words)

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