model{
   for(i in 1:N){
      Resp[i]~dbin(pA[i],Nk)
      Pred[i]~dbin(pA[i],Nk)
      percept[i]<-a*st[i,1]+b*st[i,2]
      pA[i]<-pnorm(percept[i],c,tau)
   }
   # priors
   tau<-pow(sigma,-2)
   sigma~dunif(0,50)
   a~dnorm(0,0.001)
   b~dnorm(0,0.001)
   c~dnorm(0,0.001)
}