schools <- read.table ("schools.dat", header=TRUE)
   J <- nrow(schools)
   y <- schools$estimate
   sigma.y <- schools$sd
   data <- list ("J", "y", "sigma.y")
   inits <- function() {list (theta=rnorm(J,0,100), mu.theta=rnorm(1,0,100), sigma.theta=runif(1,0,100))}
   parameters <- c("theta", "mu.theta", "sigma.theta")
   schools.sim <- bugs(data, inits, parameters, "schools.bug", n.chains=3, n.iter=1000) (这句总是提示错误！说Error in eval.with.vis(expr, envir, enclos) :   could not find function "bugs"，数据在附件中，请高手指教！)
   print (schools.sim)
   plot (schools.sim)