# Congdon P., pag. 17, Example 2.1  Systolic blood pressure
#
# Short description. 
# Suppose we take a random sample of 20 systolic blood pressure 
# readings y_i from a subpopulation of adult men.
# We know from national surveys that sigma =13.
# We are interested in estimating mu, the mean blood pressure in the  
# particular diagnostic group of our study, and predicting its likely
# level in a typical new patient in the same diagnostic group.
# Suppose we select a non informative prior regarding mu.
# Suppose we know the typical blood pressure for all adult males is
# 125, and we wish to test whether the particular diagnostic group
# has above or below average pressure 

# Program 2.1 Systolic Blood Pressure
# downloaded from 
# http://www.mrc-bsu.cam.ac.uk/bugs/weblinks/webresource.shtml
# 
model {# known variance
  sigma2 <- 169;
# precision = 1/variance
  tau <-1/sigma2;
#  Prior on normal mean
  mu ~ dnorm(0,0.00001);
# likelihood
  for (i in 1:N) { y[i]   ~ dnorm(mu,tau)}
# samples where H0 holds
  p.above <- step(mu-125);
# samples where H1 holds
  p.below <- step(125-mu);
# prediction for 'new' patient
  y.new ~ dnorm(mu,tau) }

Data
list(N=20,
y=c(98,160,136,128,130,114,123,134,128,107,123,125,129,132,154,
115,126,132,136,130))