[R] Help R2WinBUGS

TTsai t.tsai at wustl.edu
Thu Dec 3 05:38:32 CET 2009


Hello,

I have problem running WinBUGS from R.
The following example works in WinBUGS but it does not work in R through
package R2WinBUGS.
Does anyone know what the problem is?

x <- c(0.2, 1.1, 1, 2.2, 2.5, 2.9, 2.9, 3.6, 3.8, 0.6, 1, 2, 2.4, 2.6, 2.8,
3.2, 3.9, 3.5)
y <- c(0.5, 1.3, 0.1, 0.7, -0.4, 0.5, -0.9, -0.3, -0.3, 0.6, 0.4, 0.9, -0.1,
-0.4, -0.5, -0.2, 0.3, -1.5)
eco <- c(1, 3, 1, 2, 1, 2, 1, 1, 2, 1, 1, 3, 2, 3, 2, 2, 2, 1)

N <- length(y)
J <- length(unique(eco))

f.data <- list("N", "y", "x", "eco", "J")
f.inits <- function(){
               list(sigma.y=1, beta.0=1, beta.x=1, beta.eco=c(NA, 1, 1))}
f.parameters <- c("beta.0", "beta.x", "sigma.y", "beta.eco")

f.ml <- bugs (data=f.data, 
               inits=f.inits, 
               parameters.to.save=f.parameters, 
               model.file="oecd1.bug",              
               n.chains=3,                     
               n.iter=1000,                       
               debug=TRUE)


# This code works in WinBUGS.

model {
  # dummy variable
  for (i in 1:N){ 
  D.eco2[i] <- equals(eco[i],2)  
  D.eco3[i] <- equals(eco[i],3)
  }  
  # model's likelihood
  for (i in 1:N){                          
    y[i] ~ dnorm (mu[i], tau.y)      
    mu[i] <- beta.0 + beta.x*x[i] + beta.eco[2]*D.eco2[i] +
beta.eco[3]*D.eco3[i]      
  }
  # 
  beta.eco[1] <- 0
  
  # priors
   beta.0 ~ dnorm (0, 0.0001)
   beta.x ~ dnorm (0, 0.0001)
   
   for (j in 2:J){ 
   beta.eco[j] ~ dnorm (0, 0.0001)  
   }    
   
   tau.y <- pow(sigma.y, -2)         
   sigma.y ~ dunif (0, 100)           
} 


DATA 
list(N=18, J=3,
x = c(0.2, 1.1, 1, 2.2, 2.5, 2.9, 2.9, 3.6, 3.8, 0.6, 1, 2, 2.4, 2.6, 2.8,
3.2, 3.9, 3.5),
y = c(0.5, 1.3, 0.1, 0.7, -0.4, 0.5, -0.9, -0.3, -0.3, 0.6, 0.4, 0.9, -0.1,
-0.4, -0.5, -0.2, 0.3, -1.5),
eco = c(1, 3, 1, 2, 1, 2, 1, 1, 2, 1, 1, 3, 2, 3, 2, 2, 2, 1)
)

INITIAL VALUES 
list(sigma.y=1, beta.0=1, beta.x=1, beta.eco=c(NA, 1, 1))
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