[R-sig-ME] Query

[Doran, Harold]

Perhaps a bit OT, but what *is* an interaction between a fixed and random factor? The fixed effects are estimates, BLUPs are not estimates really.

I can't quite consider what the estimand is in this instance

-----Original Message-----
From: R-sig-mixed-models [mailto:r-sig-mixed-models-bounces at r-project.org] On Behalf Of Ben Bolker
Sent: Wednesday, September 13, 2017 2:34 PM
To: r-sig-mixed-models at r-project.org
Subject: Re: [R-sig-ME] Query


   I'm going to say something here to get the conversation started, but this information comes with a giant caveat.  I hope that someone with more knowledge of experimental designs comes forward ...

  in general an interaction between a random factor r and a fixed factor f is either

(1|r:f)

(assuming a positive, compound-symmetric variance-covariance matrix) or

(f|r)

(assuming an unstructured variance-covariance matrix).  The latter is likely to be very expensive if f has more than a few levels.

  Interaction between two random factors would be (1|r1:r2) (you would have (1|r1) and (1|r2) in the model as well).

On 17-09-13 02:12 PM, EZEQUIEL ROSSI wrote:
> Dears,
> 
> 
> I am working with a Federer's augmented block design in lmer function 
> and I need indicate interaction between ramdom and fixed factors and 
> between two ramdom factors . Can you say me how I should make this?
> 
> 
> Thank you very much,
> 
> 
> Best regards,
> 
> 
> Ezequiel Rossi
> 
> [[alternative HTML version deleted]]
> 
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