[R-sig-ME] On what basis one of the predictors/fixed factors should be included in a random slope model?

Saudi Sadiq ss1272 at york.ac.uk
Sun Apr 10 22:09:33 CEST 2016


Hi Alex,
Many thanks for your reply and the historical FB thread.
Best

On 9 April 2016 at 17:09, Alex Fine <abfine at gmail.com> wrote:

> You may want to check out the response to that paper, which was pretty
> well received:  http://arxiv.org/abs/1506.04967
>
> Somewhat unconventionally, here is a facebook thread where a subset of the
> authors of each paper talked about it:
> https://www.facebook.com/alex.b.fine.9/posts/10102858621451518
>
> A couple quick notes:
>
> 1.  I think the basic consensus is that, when using LMMs for hypothesis
> testing, you must use the random effects to do what virtually every other
> framework for hypothesis testing does, which is account for sources of
> variation that may lead to Type I error.  So if "gender" is an experimental
> manipulation that might vary depending on item, you should include it.
>
> 2.  Does it make sense to have a by-speaker random slope for gender?  This
> implies that a given speaker could have either gender.  Without getting too
> far afield, I doubt this was indeed the case in your design.  In the
> terminology of the Barr et al. paper, a by-speaker random slope for gender
> is not "justified by the design".
>
> 3.  Do not trust or report a model with an error warning.
>
> On Sat, Apr 9, 2016 at 11:35 AM, Saudi Sadiq <ss1272 at york.ac.uk> wrote:
>
>> I read this paper  'Random effects structure for confirmatory hypothesis
>> testing: Keep it maximal' by Barr, Levy, Scheepers and Tily (2013) and
>> enjoyed it. I tried, then, to keep it maximal with a dataset I am
>> analysing
>> but I am facing a problem (this may look naive). I hope you will help me
>> solve it. The dataset includes 9 predictors and I am using R. The model I
>> ran is:
>>
>> modle1<- glmer(convergence ~ gender + age.group
>> +education+residence+sound_before+sound_after+ part.of.speech +
>> grammatical.gender + style + (1|speaker) + (1|item), data = qaaf,
>> family='binomial', control = glmerControl(optimizer = "bobyqa"), nAGQ = 1)
>>
>> As you see, I have two random factors (speaker and item).
>> Q1: On what basis one of the predictors/fixed factors should be included
>> in
>> a random slope model?
>> The model with random slopes could be like model2 or model3:
>>
>> modle2<- glmer(convergence ~ gender + age.group
>> +education+residence+sound_before+sound_after+ part.of.speech
>> + grammatical.gender + style + (1+gender|speaker) + (1+education|item),
>> data = qaaf,  family='binomial', control = glmerControl(optimizer =
>> "bobyqa"), nAGQ = 1)
>>
>> modle3<- glmer(convergence ~ gender + age.group
>> +education+residence+sound_before+sound_after+ part.of.speech +
>> grammatical.gender + style + (1+residence|speaker) + (1+residence|item),
>> data = qaaf,  family='binomial', control = glmerControl(optimizer =
>> "bobyqa"), nAGQ = 1)
>>
>> Model2 has gender and education included in the random slope and model3
>> has
>> residence alone.
>> Q2: Should the fixed factor used in a random slope model be the same (as
>> in
>> model3)?
>> Q3: If  it is okay for such a model to have  two fixed factors (as in
>> model2)
>> or just one (as inmodel3), which is better?
>> Q4: What should be done if the model does not converge with a random
>> slope,
>> is there a way to make it work? Or can i trus and report the results of
>> the
>> model even if there is a warning message?
>>
>> Best regards
>>
>>
>> --
>> Saudi Sadiq,
>> Assistant Lecturer, English Department,
>> Faculty of Al-Alsun,Minia University,
>> Minia City, Egypt &
>> PhD Student, Language and Linguistic Science Department,
>> University of York, York, North Yorkshire, UK,
>> YO10 5DD
>> http://york.academia.edu/SaudiSadiq
>> https://www.researchgate.net/profile/Saudi_Sadiq
>> Certified Translator by Egyptian Translation Association (Egyta)
>> <http://www.egyta.com/>
>> Certified Interpreter by Pearl Linguistics
>> <http://www.pearllinguistics.com/>
>> Verified Teacher at https://lingos.co/users/saudi-sadiq
>> Verified Teacher at
>> https://www.firsttutors.com/uk/languages/teacher/saudi.arabic.english
>>
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>>
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>>
>
>
>
> --
> Alex Fine
> Ph. (336) 302-3251
> web:  http://internal.psychology.illinois.edu/~abfine/
> <http://internal.psychology.illinois.edu/~abfine/AlexFineHome.html>
>



-- 
Saudi Sadiq,
Assistant Lecturer, English Department,
Faculty of Al-Alsun,Minia University,
Minia City, Egypt &
PhD Student, Language and Linguistic Science Department,
University of York, York, North Yorkshire, UK,
YO10 5DD
http://york.academia.edu/SaudiSadiq
https://www.researchgate.net/profile/Saudi_Sadiq
Certified Translator by Egyptian Translation Association (Egyta)
<http://www.egyta.com/>
Certified Interpreter by Pearl Linguistics
<http://www.pearllinguistics.com/>
Verified Teacher at https://lingos.co/users/saudi-sadiq
Verified Teacher at
https://www.firsttutors.com/uk/languages/teacher/saudi.arabic.english

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