Can GMRFs be constructed for non-spatial data? [question via email]

[ericward-noaa]

Yes, here's a recent example illustrating this with salmon, where they used a GMRF based model to model covariation between body size and migration timing of salmon
https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.14760

An important thing they point out is that because the scale of covariation is different between size / migration timing, only anisotropic models should be considered.