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Sextus Empiricus
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More than semantics

As Gordon Smyth mentions in the comments, it is more than just semantics. Due to the parameter $\phi_1$ the logistic growth model is not exactly equal to the logistic function used in logistic regression.

Compare

$$\phi_1/\lbrace 1+\text{exp}[-(t-\phi_2)/\phi_3]\rbrace$$

with

$$1/\lbrace 1+\text{exp}[-(t-\phi_2)/\phi_3]\rbrace$$

Logistic regression and fractions

Logistic regression deals with $\phi_1=1$. This relates to fractions between zero and one. The example from the book is a growth model and a different setting.

Not all fractions are logistic regression

Sidenote: I am saying that logistic regression relates to fractions, but not all fractions relate to logistic regression.

When we deal with fractions then we still might have $\phi_1 \neq 1$ for instance the fraction of coronavirus variants relates to growth models, and has been modeled by some with logistic curves that wrongly assume $\phi_1 = 1$.

Sextus Empiricus
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