Access theta from random effect model in plm()-CodePudding

I am running a random effects model and would like to take the theta object (the quasi-demeaned variance) and store it to an object. Looking around, it is not clear what this is stored as in a plm() object or where it comes from when I run the summary() function.

Here’s an example of code:

library(plm)
data("Produc", package = "plm")
zz <- plm(log(gsp) ~ log(pcap)   log(pc)   log(emp)   unemp, 
    data = Produc, index = c("state", "year"),
    model = "random")

summary(zz)

...
Effects:
                   var  std.dev share
idiosyncratic 0.001454 0.038137 0.175
individual    0.006838 0.082691 0.825
theta: 0.8888
...

I thought I might access it by doing theta <- zz$theta but that returns NULL.

Anyone more familiar with how this package works who could give advice would be much appreciated!

CodePudding user response：

The ercomp element of the model object contains the estimation of various component errors. You perhaps mean to get theta from zz$ercomp$theta; however, you do not have a random effects model in your original post?