winbugs运行线性方程数据可成功输出结果。利用R中R2WINBUGS无法得出结果，代码如下。

问题出错在最后！！

#winbugs中可成功运行#
model
{ for( i in 1 : N ) {
y[i] ~ dnorm(mu[i], tau)
mu[i] <- alpha+beta1 * x1[i] + beta2 * x2[i] + beta3 * x3[i] +
beta4* x4[i]
}
alpha ~ dnorm(0.0,1.0E-6)
beta1 ~ dnorm (0.0,1.0E-6)
beta2 ~ dnorm (0.0,1.0E-6)
beta3 ~ dnorm (0.0,1.0E-6)
beta4 ~ dnorm (0.0,1.0E-6)
tau ~ dgamma(0.001,0.001)
sigma <- 1 / sqrt(tau)
}
list(y = c(11.2, 8.8, 12.3, 11.6, 13.4, 18.3, 11.1, 12.1, 9.6, 8.4, 9.3, 10.6, 8.4, 9.6, 10.9,
10.1, 14.8, 9.1, 10.8, 10.2, 13.6, 14.9, 16, 13.2, 20, 13.3, 10.4),
x1 = c(5.68, 3.79, 6.02, 4.85, 4.6, 6.05, 4.9, 7.08, 3.85, 4.65, 4.59, 4.29, 7.97, 6.19,
6.13,5.71, 6.4, 6.06, 5.09, 6.13, 5.78, 5.43, 6.5, 7.98, 11.54, 5.84, 3.84),
x2 = c(1.9, 1.64, 3.56, 1.07, 2.32, 0.64, 8.5, 3.0, 2.11, 0.63, 1.97, 1.97, 1.93, 1.18,
2.06, 1.78, 2.4, 3.67, 1.03, 1.71, 3.36, 1.13, 6.21, 7.92, 10.89, 0.92, 1.2),
x3 = c(4.53, 7.32, 6.95, 5.88, 4.05, 1.42, 12.6, 6.75, 16.28, 6.59, 3.61, 6.61, 7.57,
1.42, 10.35, 8.53, 4.53, 12.79, 2.53, 5.28, 2.96, 4.31, 3.47, 3.37, 1.2, 8.61, 6.45),
x4 = c(8.2, 6.9, 10.8, 8.3, 7.5, 13.6, 8.5, 11.5, 7.9, 7.1, 8.7, 7.8, 9.9, 6.9, 10.5, 8.0,
10.3, 7.1, 8.9, 9.9, 8.0, 11.3, 12.3, 9.8, 10.5, 6.4, 9.6),N = 27)

list(alpha = 0.5, beta1 = 0.5, beta2 = 0.5, beta3 = 0.5, beta4 = 0.5, tau = 0.5)


      然后相同代码修改格式导入R中
#output.bug#
model
{
for(i in 1:N){
y[i]~dnorm(mu[i],tau)
mu[i]<-alpha+beta1*x1[i]+beta2*x2[i]+beta3*x3[i]+beta4*x4[i]
}
alpha~dnorm(0.0,1.0E-6)
beta1~dnorm (0.0,1.0E-6)
beta2~dnorm (0.0,1.0E-6)
beta3~dnorm (0.0,1.0E-6)
beta4~dnorm (0.0,1.0E-6)
tau~dgamma(0.001,0.001)
sigma<-1/sqrt(tau)
}

library(R2WinBUGS)
data=list(y,x1,x2,x3,x4,N)
inits=function(){list(alpha = 0.5, beta1 = 0.5, beta2 = 0.5, beta3 = 0.5, beta4 = 0.5, tau = 0.5)}
output=bugs(data,inits,model.file="output.bug",parameters=c("alpha","beta","tau"),n.chains = 1,n.iter=5100,n.burnin=100,n.thin=1,bugs.directory="D:/WinBUGS14/",codaPkg=FALSE,debug=TRUE)

#log#出现问题
variable N is not defined
     .....

问题到底出现在哪一步。。。WINBUGS都可以成功运行的啊。。。