[R] Left censored responses in mixed effects models

[Giovanni Parrinello]

Dear Bert,
a solution is the 'package'
censre3 by  Hughes JP
Reference: Hughes JP: Mixed effects models with censored data with 
application to HIV RNA levels.  Biometrics, 55:625-629, 1999.

Giovanni

Don MacQueen ha scritto:
> I assume you've looked at the NADA package(?) While I don't believe it 
> goes as far as dealing the mixed effects models, it might give you a 
> starting point, and possibly some additional references.
>
> -Don
>
> At 9:08 AM -0700 5/12/08, Bert Gunter wrote:
>> Dear R Fellow-Travellers:
>>
>> What is your recommended way of dealing with a left-censored response
>> (non-detects) in (linear Gaussian) mixed effects models?
>>
>> Specifics: Response is a numeric positive measurement (of volume, 
>> actually);
>> but when it falls below some unknown and slightly random value 
>> (depending on
>> how the sample is prepared and measured), it cannot be measured and is
>> recorded as 0.
>>
>> There is some statistical literature on this, but I was unable to find
>> anything that appeared to me to implement a strategy in any R 
>> package. If it
>> matters, I am less interested in inference than in removing possible 
>> bias in
>> estimation.
>>
>> Feel free to respond off-list if you feel that this would not be of 
>> general
>> interest.
>>
>> Cheers,
>>
>> Bert Gunter
>> Genentech
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>
>


-- 
dr. Giovanni Parrinello
Department of Biotecnologies
Medical Statistics Unit
University of Brescia
Viale Europa, 11 25123 Brescia
email: parrinel at med.unibs.it
Phone: +390303717528
Fax: +390303717488