The model function for the quadratic model is defined as $$ f(d,\theta)=E_0+\beta_1d+\beta_2d^2$$
quadratic(dose, e0, b1, b2)Dose variable
Placebo effect
beta1 parameter
beta2 parameter (controls, whether model is convex or concave)
Response value
This model is intended to capture a possible non-monotonic dose-response relationship.
Pinheiro, J. C., Bretz, F. and Branson, M. (2006). Analysis of dose-response studies - modeling approaches, in N. Ting (ed.). Dose Finding in Drug Development, Springer, New York, pp. 146--171
logistic, sigEmax,
linlog, linear, exponential,
emax, betaMod