本人摸索用winbugs估计SV模型过程中遇到了的问题如下：在specification tool 窗口按compile时出现了错误提示
array index is greater than array upper bound for y！！如何解决啊？？？
具体的模型，和数据设置如下
model
{
for (t in 1:n){yisigma2[t]<-1/exp(theta[t])
y[t] ~ dnorm(0,yisigma2[t])
}
mu~dnorm(0,0.1)
phistar~dbeta(20,1.5)
itau2~dgamma(2.5,0.025)
beta<-exp(mu/2)
phi<-2*phistar-1
tau<-sqrt(1/itau2)
theta0~dnorm(mu,itau2)
thmean[1]<-mu+phi*(theta0-mu)
theta[1]~dnorm(thmean[1],itau2)
for(t in 2:n) {thmean[t]<-mu+phi*(theta[t-1]-mu)
theta[t]~dnorm(thmean[t],itau2)
}
}

list(n=20,y=c(0.01965，0.0234，0.05664，0.047704，0.029483，0.01203，0.003767，0.007112，0.000838，0.0325，0.02449，0.00015,0.042398，0.045487，0.001113，0.022363，0.03888，0.033397，0.035908，0.022705))
求高人指点