[R-sig-ME] lme4/nlmer problem

[Kalle Eerikäinen]

Hi Markus,

Many thanks for your message. Unfortunately, it makes no change whether 
or not the argument "fixed=p0+p1~1" is included into the model formula.

Kalle

Markus Jäntti wrote:
> Kalle Eerikäinen wrote:
>> Hello,
>>
>> I have done some test estimations using the lme4 package of R. The 
>> estimation of the parameters of linear mixed-effect models using the 
>> 'lmer' goes well. For instance, a very simple single-level mixed model 
>> "Naslund_lmer1  <- lmer(y ~ d13 + (1 |stand), data = height1)" for the 
>> relationship between the tree height (or its transformation) and 
>> diameter comes out perfectly.
>>
>> However, if I attempt to estimate nonlinear mixed-effect models, I 
>> always receive an error message that tells me: "Error: 
>> length(start$fixed) is not TRUE". This is also the case with the 
>> following model:
>>
>> Schumacher_nlmer1 <- lme4:::nlmer(ht   ~ exp(p0 + p1*1/d13)+u0 ~ 
>> (u0|stand) , fixed=p0+p1~1, data = height1, start = c(p0 = 0.1, p1 = 
>> -9.0), verb = 1)
> 
> What is the purpose of the argument "fixed=p0+p1~1"? The help page makes 
> no mention of it. Maybe this is what is generating the error message.
> 
> markus
>>
> 
> 
>> It is obvious that there exists a trivial bug/mistake in my code, but 
>> I cannot see what is wrong with it. Could someone give me a helping 
>> hand with my 'nlmer problem'?
>>
>> Regards,
>>
>> Kalle Eerikäinen
>>
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> R-sig-mixed-models at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
> 
>