Hi, I have problems writing a script for a logistic model. My data looks something like this: PI A N1 N2 N3 0 9 0 1 0 1 4 1 0 1 0 8 0 0 0 1 6 0 1 0 And so on? The model I want to fit looks like this: PI=exp^f(sw)/1+exp^f(sw) where f(sw)=c+(a1*N1/A^z)+(a2*N2/A^z)+(a3*N3/A^z) So I want to estimate c,a1,a2,a3 and z? Is there someone who can help me on this problem, because I don?t even know how to start. Best, Anna -- View this message in context: http://r.789695.n4.nabble.com/writing-my-own-logistic-regression-function-tp4630843.html Sent from the R help mailing list archive at Nabble.com.