As a matter of history, I believe that logistic as a growth curve came
long before the logistic as a CDF, but as Jay implies, between friends
it's the same equation.
There are some historical references on this within
SJ-8-1 gr0032 . . . . . . . Stata tip 59: Plotting on any transformed
scale
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N.
J. Cox
Q1/08 SJ 8(1):142--145 (no
commands)
tip on how to graph data on a transformed scale
Nick
[email protected]
Verkuilen, Jay
>>To be more precise, the proposed model is a gamma density kernel, not
a
bonafide gamma density ,which integrates on 1. Of course in this
context, the function is used to model nonlinear trend, not a
probability distribution of some random variable.>>
Right, and thus it's not dissimilar from using the logistic CDF as a
model for growth between asymptotes, which is often done using, say,
Gaussian errors around the curve itself.
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