How to fit a customised Non linear model using multiple parameters
I have a non linear model for which I have created a new column with formula below. The model is described as being similar to a Sigmoidal curve with two defined stages for which I have three parameters characterizing each stage. An initial stage described by K1, Y1 and P1 parameters and a second stage described by K2, Y2 and P2 parameters. Also, for each parameter I have created a new column an a...