[R-sig-ME] interpreting Std. error from glmer output
Christine Griffiths
Christine.Griffiths at bristol.ac.uk
Tue Sep 15 18:28:30 CEST 2009
Thank you for your help. Because I am using glmer with Binomial family I
cannot calculate 95% CIs using the mcmcsamp function and have not been able
to find a way to do this. Hence my reason to look at the SE.
I probably didn't explain myself clearly enough. What I meant is, is the SE
for a fixed effect the difference from the intercept, just as the mean for
a fixed effect needs to be calculated as a difference from the intercept?
Your definition earlier seemed to support that it is a difference and so I
need to calculate the SE by summing the value given with the intercept.
--On 15 September 2009 23:32 +1000 William Morris <wkmor1 at gmail.com> wrote:
> Well, it depends.
>
> It depends on what you mean by deviance, you should clarify this (here
> is a start http://en.wikipedia.org/wiki/Deviance_%28statistics%29). In
> general, deviance is used as a measure of model fit and usually
> encountered as a component of Information criteria.
>
> Do you need to take the uncertainty (SE) in model estimates into
> account? It is probably a good idea if you are going to make predictions
> based on model estimates to also calculate predictions at the 95CI
> limits.
>
> On 15/09/2009, at 10:26 PM, Christine Griffiths wrote:
>
>> Thank you. So to clarify, I do not need to calculate the deviance of
>> the standard error from the intercept standard error, in the way
>> that I would do for the estimate?
>>
>> Cheers
>> Christine
>>
>> --On 15 September 2009 21:38 +1000 Will Morris <wkmor1 at gmail.com>
>> wrote:
>>
>>> The SE is a measure of the models uncertainty about the parameter
>>> estimates, it takes into account your sample size as well as sample
>>> variance. +_2*SE is usually a good estimate of the 95% confidence
>>> interval. In other words your treatment effect for treatment2 is
>>> probably somewhere between -.6 and -.86.
>>>
>>>
>>> On Tue, Sep 15, 2009 at 8:05 PM, Christine Griffiths
>>> <Christine.Griffiths at bristol.ac.uk> wrote:
>>>
>>> I want to plot my predictions from a model and use the standard error
>>> output as a measure of dispersion as I am unable to calculate
>>> confidence
>>> intervals with mcmcsamp as I have a binomial distribution.
>>>
>>> I know that the estimates are deviations from the intercept.
>>> Fixed effects below:
>>> Estimate Std. Error z value Pr(>|z|)
>>> (Intercept) 2.90836 0.34041 8.544 < 2e-16 ***
>>> treatment2 -0.73507 0.12986 -5.660
>>> 1.51e-08
>>> ***
>>> treatment3 -1.20052 0.12371 -9.705 < 2e-16 ***
>>>
>>> So the estimate for treatment 2 is 2.9 + -0.73. Are standard errors
>>> also
>>> deviations from the intercept? i.e. 0.34 + 0.13 for treatment 2?
>>>
>>> Many thanks
>>> Christine
>>>
>>> _______________________________________________
>>> R-sig-mixed-models at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
>>>
>>>
>>>
>>>
>>> --
>>> Will Morris
>>> Masters of Philosophy candidate
>>> Vesk Plant Ecology Lab
>>> The School of Botany
>>> The University of Melbourne
>>> Australia
>>> Phone: +61 3 8344 0120
>>> http://www.botany.unimelb.edu.au/vesk/
>>
>>
>>
>> ----------------------
>> Christine Griffiths
>> PhD student
>> School of Biological Sciences
>> University of Bristol
>> Woodland Road
>> Bristol BS8 1UG
>> Tel: 0117 9287593
>> Fax 0117 3317985
>> Christine.Griffiths at bristol.ac.uk
>> http://www.bio.bris.ac.uk/research/mammal/tortoises.html
>
>
>
> Will Morris
> Masters of Philosophy candidate
> Vesk Plant Ecology Lab
> The School of Botany
> The University of Melbourne
> Australia
> Phone: +61 3 8344 0120
> http://www.botany.unimelb.edu.au/vesk/
----------------------
Christine Griffiths
PhD student
School of Biological Sciences
University of Bristol
Woodland Road
Bristol BS8 1UG
Tel: 0117 9287593
Fax 0117 3317985
Christine.Griffiths at bristol.ac.uk
http://www.bio.bris.ac.uk/research/mammal/tortoises.html
More information about the R-sig-mixed-models
mailing list