Talk:Generalised logistic function

Untitled
Hello,

I used the function given for Generalised logistic function, entered the values given for the sample graph, and did NOT get the graph given in the page entry; indeed the graph is backwards. I think there is an error in the values given for the example.

Justkenplease (talk) 17:54, 11 February 2009 (UTC)

Hi,

Same thing here. I've generated a graph in order to replace the one in the page, but I'll have to wait until my user is autoconfirmed to upload it (4 days and 10 edits from now).

Debiatan (talk) 07:37, 9 July 2009 (UTC)

I've changed the plot and it now matches the function described in the article. I'm not sure about the correctness of the whole article since I don't have the right subscriptions to read the reference "Richards, F.J. 1959 A flexible growth function for empirical use. J. Exp. Bot. 10: 290--300." The function is described in quite different terms in: http://www.horticultureandlandscape.rdg.ac.uk/hlm_richards.htm I'm worried specially by B and M being multiplied: Y = A + (H-A) / ( 1 + T*EXP( -B*( x - M )) )^(1/T) and not added, as in the article.

Debiatan (talk) 09:23, 13 July 2009 (UTC)

There is definitely something wrong here. As written B can be described as a function of M (that's means one is superfluous). Furthermore as written, B is not a description of the "growth rate." In debiatan's version of the equation (above) B is a description of the "growth rate." I've asked my university library to hunt down version of the original paper. When they get back to me I'll post a correction. I expect the true function looks as written above by Debaitan.

I'm getting a different graph now than the one that Debiatan added. Has the page changed without a corresponding update to the graph? I'm using the function A + (K - A) / (1 + Q * exp(-B * (t - M)))^(1/v) with the values as stated in the legend, i.e. A=0, K=1, B=1.5, Q=ν=0.5, M=0.5 --Rhaertel80 (talk) 13:29, 31 May 2011 (UTC)

Ditto. I just ran across this page, tried drawing the graph myself, and my version doesn't match the page's version. Could someone who knows more about generalized logistic functions than I (i.e., pretty much anyone) please check this out and fix the graph, parameters, and/or function so they all match? Scott Pakin (talk) 15:42, 2 November 2012 (UTC)

Hello, I tried out different parameters and those are the ones corresponding to the image: A=0; K=1; B=3; Q=0.5; v=0.5; M=0. So a higher growth rate B and no shift value M (since the maximum growth rate is at t=0). 2001:638:50F:2:9802:A06D:C53F:D723 (talk) 15:44, 18 October 2013 (UTC)

Modeling COVID-19 infection trajectory
Does this really belong in this article? 93.138.16.132 (talk) 11:15, 5 June 2021 (UTC)

Seconded. The reference here feels inverted. 97.113.73.95 (talk) 04:04, 18 June 2021 (UTC)