[R-sig-ME] Error in MEEM(object, conLin, control$niterEM) : Singularity in backsolve at level 0, block 1 in LME model

[Ben Bolker]

   You have constructed a model with multicollinear predictors (another 
way to put this is that your model matrix is rank-deficient).  R's 
formula interface usually takes care of discarding redundant columns, 
but when interactions are spelled out explicitly with it can't always 
manage. You might do better expressing the fixed effects component of 
the model as

(provenance + treatment + status)^2
'
As is often stated in this forum, you may have trouble fitting a random 
effect with only four levels (repetition).

   Ben Bolker

On 7/7/21 4:01 AM, Arivoara Rabarijaona wrote:
> Thank you,
> provenance:treatment is normal, nothing is unexpected
> I think the problem is with provenance:status, but I don't know how to
> resolve it.
> Using lmer, I get the message: fixed-effect model matrix is rank deficient
> so dropping 18 columns / coefficients
> 
> Ari
> 
> Le mer. 7 juil. 2021 à 09:52, romunov <romunov using gmail.com> a écrit :
> 
>> Have you tried plotting this? My guess is that you will find something
>> unexpected in the provenance:treatment level combination.
>>
>> Cheers,
>> Roman
>>
>> On Wed, Jul 7, 2021 at 9:03 AM Arivoara Rabarijaona <arivoara using gmail.com>
>> wrote:
>>
>>> Hi,
>>> I hope someone can help me. I'm using nlme to fit models.
>>>
>>> My dataframe (1785 obs) :
>>> $ id: Factor w/595 levels
>>> $ treatment: Factor w/3 levels
>>> $ provenance: Factor w/16 levels
>>> $ repetition: Factor w/4 levels
>>> $ bloc: Factor w/66 levels # nested to repetition
>>> $ response: num ... (1777 obs and 8 NA) # 3 repeated measures by id
>>> $ status: Factor w/3 levels, "dominant","codominant","suppressed" # there
>>> are 6 provenances without suppressed trees
>>>
>>> I want to run a modele like this :
>>>
>>> modele <- lme(response  ~ provenance + treatment + provenance:treatment +
>>> status + status:treatment + statuts:provenance,
>>>                     random = ~ 1|repetition/bloc,
>>>                     correlation = corAR1(form = ~ 1|repetition/bloc/id),
>>>                     data, method= "ML", na.action =na.omit)
>>>
>>> I get the message :
>>> Error in MEEM(object, conLin, control$niterEM) :   Singularity in
>>> backsolve
>>> at level 0, block 1 in LME model
>>>
>>> If I run the modele without the interaction statuts:provenance, it works.
>>>
>>> Can anyone tell me how to resolve this error ?
>>>
>>> Thanks,
>>> Arivoara Rabarijaona
>>>
>>>          [[alternative HTML version deleted]]
>>>
>>> _______________________________________________
>>> R-sig-mixed-models using r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
>>>
>>
>>
>> --
>> In God we trust, all others bring data.
>>
> 
> 	[[alternative HTML version deleted]]
> 
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