[R-sig-ME] Setting start values for log binomial model in glmmPQL

[Jennifer Yourkavitch]

Yes, I think you're right. A friend pointed out that I need to specify the coefficients for the fixed effects only.
Thanks,
Jennifer


> On May 2, 2016, at 2:40 PM, Thierry Onkelinx <thierry.onkelinx at inbo.be> wrote:
> 
> Dear Jennifer,
> 
> Are you sure that the result of c(coefini,1, 0) is a vector of length 16? The output of c() could be something else than a vector.
> 
> Best regards,
> 
> 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 
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> 
> 2016-05-01 23:20 GMT+02:00 Jennifer Yourkavitch via R-sig-mixed-models <r-sig-mixed-models at r-project.org>:
>> Hello,
>> I'm having trouble setting starting values and   I think there is a problem with my syntax for the “start” command.
>> 
>> 
>> First, I’m trying to use the coefficients from a logit model as start values for the log binomial model I want to run:
>> 
>> coefini=coef(glmmPQL(anybf~n_dis +mage_r+mage_sq+married+parity_r+nhblack+hisp+nhasian+mom_lths+mom_sclg+mom_ba+mwork+medicaid+nodad+mom_foreign,
>>      random=~1|grptr0010,family = binomial))
>> summary(coefini)
>> 
>> #coefini model looks good and runs
>> 
>> fit2<-glmmPQL(anybf~n_dis +mage_r+mage_sq+married+parity_r+nhblack+hisp+nhasian+mom_lths+mom_sclg+mom_ba+mwork+medicaid+nodad+mom_foreign,
>>      random=~1|grptr0010,family = binomial(log),start=c(coefini,1, 0))
>> 
>> summary(fit2)
>> 
>> I get this error:
>> Error in glm.fit(x = c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  :
>>   length of 'start' should equal 16 and correspond to initial coefs for c("(Intercept)", "n_dis", "mage_r", "mage_sq", "married", "parity_r", , "nhblack", "hisp", "nhasian", "mom_lths", "mom_sclg", "mom_ba", , "mwork", "medicaid", "nodad", "mom_foreign")
>> 
>> -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>> So then I tried typing in the coefficients from the logit model directly:
>> 
>> fit2<-glmmPQL(anybf~n_dis +mage_r+mage_sq+married+parity_r+nhblack+hisp+nhasian+mom_lths+mom_sclg+mom_ba+mwork+medicaid+nodad+mom_foreign,
>>               random=~1|grptr0010,family = binomial(log),start=c(0.0675, -0.127, 0.008, -0.0002, 0.369, -0.111, -0.0795, 0.363, 0.1387, -0.121, 0.415, 0.861, 0.023, -0.033, -0.307, 0.915))
>> summary(fit2)
>> 
>> And I get this error:
>> Error: cannot find valid starting values: please specify some
>> 
>> 
>> Can you see the problem?
>> 
>> Thanks!
>> Jennifer
>> 
>> 
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>> 
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