[R] Correlation structures in gls with repeated measurements

[t03eh7 at abdn.ac.uk]

Thank you, it looks like that was the problem

Emma


> Emma,
>
> It looks like there is at least one location that has been sampled at
> least twice in some year. A co-worker of me got similar errors. After
> checking his data carefully he found a duplicate row. Removing the
> duplicate row solved his problem.
>
> HTH,
>
> Thierry
>
>
> ------------------------------------------------------------------------
> ----
> ir. Thierry Onkelinx
> Instituut voor natuur- en bosonderzoek / Research Institute for Nature
> and Forest
> Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
> methodology and quality assurance
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> tel. + 32 54/436 185
> Thierry.Onkelinx at inbo.be
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>
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>
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>
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>
> -----Oorspronkelijk bericht-----
> Van: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> Namens t03eh7 at abdn.ac.uk
> Verzonden: woensdag 2 juli 2008 12:29
> Aan: r-help at r-project.org
> Onderwerp: [R] Correlation structures in gls with repeated measurements
>
> Hi,
>
> I am trying include a spatial correlation structure into a gls model but
> keep getting the following error:
>
>> ocean<-read.table("C:\\oceanography2.txt",header=TRUE)
>> library(nlme)
>
>> YEAR<-as.factor(ocean$YEAR)
>
>>group<-groupedData(san_dens~temp_grad*pyc_grad*start_thermo|YEAR,data=o
> cean)
>
>> model1<-gls(san_dens~temp_grad*pyc_grad*start_thermo,data=group)
>
>> model2<-update(model1,corr=corSpher(form=~MIDLONGDEC+MIDLATDEC|YEAR))
> Error in getCovariate.corSpatial(object, data = data) :
>   Cannot have zero distances in "corSpatial"
>
>
> The measurements have been repeated over 10 years so the coordinates are
> repeated which I assume is the reason for this error. I thought grouping
> by YEAR should remove this but it doesnt seem to work, or I am making a
> mistake when I am trying to group it? I have noticed a couple of other
> posts with the same problem but I have still not managed to solve this.
>
> I would be really grateful if anyone has any ideas or has had this
> problem
> before.
>
>
> Thanks in advance,
> Emma Hazard
>
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