[R-sig-ME] Question about random effects

[Ben Bolker]

  I agree, although I'll also say that if you are faced with a power
imbalance (reviewer/supervisor/etc. insists that it should be removed),
in the case where the random effect variance is estimated as zero there
is really very little (no?) *practical* difference in this case between
keeping or removing the random effect. In particular, the estimates of
any other variance components in the model, as well as all of the
contents of summary() [point estimates and Wald standard errors of
fixed-effect of coefficients] should be identical (try it and see).

  cheers
    Ben Bolker


On 16-05-23 11:42 AM, Thierry Onkelinx wrote:
> If the random effect reflects the design of the study then it should remain
> in the model.
> 
> ir. Thierry Onkelinx
> Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
> Forest
> team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
> Kliniekstraat 25
> 1070 Anderlecht
> Belgium
> 
> To call in the statistician after the experiment is done may be no more
> than asking him to perform a post-mortem examination: he may be able to say
> what the experiment died of. ~ Sir Ronald Aylmer Fisher
> The plural of anecdote is not data. ~ Roger Brinner
> The combination of some data and an aching desire for an answer does not
> ensure that a reasonable answer can be extracted from a given body of data.
> ~ John Tukey
> 
> 2016-05-23 17:13 GMT+02:00 Adriana Maldonado Chaparro <
> maldonado.aa at gmail.com>:
> 
>> Greetings,
>>
>> I want to ask for advise on the following issue:
>> I fitted a mixed model where I'm trying to explain variation in Litter Sex
>> Ratio as a function of social network position. In this model the random
>> effect, individual identity, explained none of the variance, and one of the
>> reviewers argued that I should exclude it from my model because of these
>> reason. I think I should keep it because I have repeated measures. What are
>> your thoughts on this matter?
>>
>> Thanks in advance,
>>
>> Adriana Maldonado
>> Postdoctoral Researcher
>>
>>         [[alternative HTML version deleted]]
>>
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