2

Here is my problem: I need to use hupossion in MCMCglmm package. Here is my prior:

```
> prior = list(R = list(V = diag(2), nu = 0.002),
+ G = list(G1 = list(V = diag(10), nu = 0.002),
+ G2 = list(V = 1, nu = 0.002)))
```

and here is my training:

```
> myTrain <- MCMCglmm(pipenumyearnosameday ~ trait - 1 +
+ at.level(trait,1):lastyearnumnosameday +
+ at.level(trait,1):pipeInsideSizemm,
+ random = ~idh(pipematerialgroup1):installyeargroup1,
+ data = train,
+ prior = prior,
+ verbose = F,
+ pr=T,
+ family = "hupoisson",
+ rcov = ~idh(trait):units)
```

There are 5 levels in the attribute pipematerialroup1. I know sth must be wrong with the prior. I got the following information:

```
Error in MCMCglmm(pipenumyearnosameday ~ trait - 1 + at.level(trait, 1):lastyearnumnosameday + : prior$G has the wrong number of structures
```

there is one more thing I need to say:

```
myPredict <- predict(myTrain,newdata = myTest,type = "response",marginal = ~idh(trait):pipematerialgroup1,interval = "confidence")
```

This is my prediction part when I just take pipematerialgroup1 as random effect. If combine pipematerialgroup1 and installyeargroup1, what this prediction would be?

Can someone help me get the prior right? Thanks a lot.