model
{
         x        ~ dbin(theta1, n1)   #  Likelihood for group 1
         theta1   ~ dbeta(1,1)         #  Prior for theta1

         y        ~ dbin(theta2, n2)   #  Likelihood for group 2
         theta2   ~ dbeta(1,1)         #  Prior for theta2

      propdiff <- theta1-theta2        #  Calculate difference for binomial parameters
      rr <- theta1/theta2              #  Calculate relative risk
                                       #  Calculate odds ratio
      or<- theta1*(1-theta2)/((1-theta1)*theta2)

}

# Data

list(x  = 6,
     n1 = 20,
     y  = 20,
     n2 = 25)

# Results

|     node |    mean |      sd | MC error |    2.5% |  median |   97.5% | start | sample  |

|   theta1 |  0.3176 | 0.09681 | 0.001334 |   0.148 |  0.3118 |  0.5211 |  1001 |   5000  |
|   theta2 |  0.7774 | 0.07969 | 0.001067 |  0.6057 |  0.7848 |  0.9103 |  1001 |   5000  |
| propdiff | -0.4598 |  0.1254 | 0.001562 | -0.6886 | -0.4662 | -0.1937 |  1001 |   5000  |
|       or |  0.1505 |   0.112 | 0.001403 | 0.03093 |   0.122 |  0.4428 |  1001 |   5000  |
|       rr |  0.4134 |  0.1358 | 0.001762 |  0.1862 |  0.4025 |  0.7155 |  1001 |   5000  |