Change in TP values

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Jan 14, 2019, 8:24:32 AM1/14/19
to tRophicPosition
Dear Mr Claudio Quezada,

I am sending you an email as I obtain different TP values when I am working species by species or with different species at the same time.
So I obtained a different TP value with the fonction summary(posterior.grypus) (--> work on one species at the time), and with the fonction Param.TP.Grypus <- parametricTP(Grypus, lambda=3, print=TRUE) (--> more than one species at the time).

Do you know if the values are influenced by the others species in the model?

Thank you in advance for your answer,,

Best regards,

France Damseaux - PhD student
F.R.S. - FNRS Research fellow
University of Liege
Laboratory of Oceanology - MARE Center
Allée du 6 Août, 11 - B6c (2/19)
4000 Liege - Belgium

Tel : (+32) 4 366 4844
Publications on :

Claudio Quezada Romegialli

Jan 14, 2019, 3:22:22 PM1/14/19
to, tRophicPosition
Dear France

I am not sure if I understood completely your question.

parametricTP calculates the parametric version of trophic position, i.e. it should give you the same value for TP if you do the calculation by hand (see the help or

If you calculate TP with any of the Bayesian models (either several or one species at the same time), the results should not vary, as the calculation doesn't depend on the rest of species. parametricTP and the Bayesian TP likely will be different.

If you want, you can send me the raw data, the script you are using to calculate TP and I can tell you what might be wrong, if that's the case.



To download tRophicPosition package visit
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Dr. Claudio Quezada-Romegialli
Profesor Asociado
Departamento de Biología
Facultad de Ciencias Naturales y Exactas
Universidad de Playa Ancha
Teléfono: +56 32 250 0519
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