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< ASReml ~ bivariate spatial analysis

j.hadfield@ed.ac.uk

Posted: Wed Feb 22, 2012 2:29 pm

Joined: 13 Aug 2008 Posts: 18

Hi,

I would like to fit a bivariate spatial analysis with exponential covariance functions. I have succesfully got a univariate model working using mtrnv, but I'm not sure how to set up a bivariate model. In a previous post, in the context of an AR1 process Arthur has suggested something along the lines of ;

us(trait):mtrn(lat, long, phi=1)

However this fails with the error "ASReml failed to invert a spatially indexed correelation structure The data may have duplicate points or the correlations are too high."

In any case, I think that even if this could be made to work it would have the same phi for each trait whereas I would like separate phi's for each.

The bivariate model with separate phi's can be fitted in spBayes, but it does not allow me to have a cross-covariance function between the two traits with a seprate phi and this is critical to the analysis. Specifically I would like three correlation functions:

COR(y1_i, y_1j) = exp(-d/phi_1)
COR(y1_i, y_2j) = exp(-d/phi_12)
COR(y2_i, y_2j) = exp(-d/phi_2)

I was hoping that ASreml could be made to fit such a model.

Any indication of whether such a model would be possible would be great.

Cheers,

Jarrod

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