Program 2.4  Survival cancer times

model  {
 
tau.a ~ dgamma(0.0001,0.0001);
    S2[1] <- 1/tau.a
tau.b ~ dgamma(0.0001,0.0001);
     S2[2] <- 1/tau.b

    mu.a ~ dnorm(0,0.0001);
for(i in 1:2)  {mu.b[i] ~ dnorm(0,0.0001)}
# the above line corrects: mu.b[1:2] ~ dnorm(0,0.0001)

# first 'sample' model 
for (i in 1:N)  {  y.a[i] <- log(survtime[i]);
  y.a[i]  ~ dnorm(mu.a,tau.a);  }

# new obs
  z[1] ~ dnorm(mu.a,tau.a);
  above150[1] <- step(z[1]-log(150));

# second 'sample' model
  for (i in 1:N)  {  y.b[i] <- log(survtime[i]);
   G[i] <- step(age[i]-50)+1
  y.b[i]  ~ dnorm(mu.b[G[i]],tau.b);  }

# new obs in each age group
  z[2] ~ dnorm(mu.b[1],tau.b);
  z[3] ~ dnorm(mu.b[2],tau.b);
  above150[2] <- step(z[2]-log(150));
  above150[3] <- step(z[3]-log(150))  }

Data 1
survtime[] age[]
25 38
45 54
238 37
194 47
16 51
23 48
30 42
16 50
22 45
123 33
51 46
412 34
45 66
162 44
14 64
72 49
5 56
43 55
45 30
91 40

Data 2
list(N=20)

Inits
list(tau.a=1,mu.a=0,mu.b=c(0,0),tau.b=1)