BUGS example 6
Gillian Raab , Napier University
January 2001




model;
{
# vague priors for a  b and tau
   a ~ dnorm( 0.0,1.0E-6)
   b ~ dnorm( 0.0,1.0E-6)
   tau ~ dgamma(0.001,0.001)
   sd <- sqrt(1 / tau)
   for( i in 1 : N ) {
     fit[i]<-a*exp(-b*x[i])
      y[i] ~ dnorm(fit[i],tau)
   }
# calculate LD50 LD90 and LD95
ld50<-(-log(0.5)/b)
ld90<-(-log(0.1)/b)
ld95<-(-log(0.05)/b)
}

data;
list(N=12,y=c(962, 1030, 938, 689, 667, 697, 452, 445, 424, 235, 168, 193),
x=c(0, 0, 0, 2, 2, 2, 4, 4, 4, 8, 8, 8))


inits;
list(tau=1,a=1000,b=0.2)

linits;
list(tau=10,a=1000,b=.5)