[R-sig-ME] Testing whether I need a random effect?

[Ben Bolker]

Christopher David Desjardins wrote:
> Hi I have the following model:
>
> m.f <- glmer(NumCitations ~ 1 + Program + ProductType + ProductField +
> (1 | ProductDate), family="poisson",data = data)
>
> And I am wondering how I can test whether or not ProductDate needs to
> be included as a random effect or if I could just run a glm() without
> ProductDate?
>
  see http://glmm.wikidot.com/faq , "How can I test whether a random
effect is significant?" (there aren't worked examples there -- anyone
want to donate some?)