Model	Number of parameters	Formula
Null	1	y = a
Full	no. of groups	y = group mean
Exp model 3	3	y = a · exp(bxd)
Exp model 4	4	$\mathrm{y}=\mathrm{a}·(\mathrm{c}-(\mathrm{c}-1)\exp (-{\mathrm{bx}}^{\mathrm{d}}))$
Hill model 3	3	${\displaystyle \mathrm{y}=\mathrm{a}·(1-\frac{{\mathrm{x}}^{\mathrm{d}}}{{\mathrm{b}}^{\mathrm{d}}+{\mathrm{x}}^{\mathrm{d}}})}$
Hill model 4	4	${\displaystyle \mathrm{y}=\mathrm{a}·(1-\frac{(\mathrm{c}-1)·{\mathrm{x}}^{\mathrm{d}}}{{\mathrm{b}}^{\mathrm{d}}+{\mathrm{x}}^{\mathrm{d}}})}$
Inverse Exponential	4	${\displaystyle \mathrm{y}=\mathrm{a}·(1+(\mathrm{c}-1)\exp (-{\mathrm{bx}}^{-\mathrm{d}}))}$
Log‐Normal Family	4	${\displaystyle \mathrm{y}=\mathrm{a}·(1+(\mathrm{c}-1)\varphi (\mathrm{lnb}+\mathrm{dlnx}))}$