odd variogram signals

[abern...@gmail.com]

Hi, I've run into some odd variograms in my caribou data - for lack of a better description, some of them are coming out "squiggly".  Besides showing there is little evidence for range residency, Im not sure how to interpret these.  What would cause this signal?  

The satellite collars I'm analyzing have a programmed geofence - within a certain area, sampling is hourly, outside the area sampling is 3 times a day.  Would switching between the sampling regimes cause this "squiggly" signal?  

Thanks for taking a look!  R

[Jesse Alston]

Hi Robin,

This is pretty common, and as you guessed, is caused by the differing sampling intervals. You can account for it in the variogram using dt=c(1,8) %#% “hour” in the variogram function.

Jesse

Sent via mobile--I apologize for excess brevity

On Aug 19, 2022, at 2:45 PM, abern...@gmail.com <abern...@gmail.com> wrote:

Hi, I've run into some odd variograms in my caribou data - for lack of a better description, some of them are coming out "squiggly".  Besides showing there is little evidence for range residency, Im not sure how to interpret these.  What would cause this signal?  

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[abern...@gmail.com]

Thanks Jesse!  

I did as you suggested, adding the dt as an argument to my variogram function and It did clean things up for sure!  Can you help me understand how it's working?  I couldn't find any documentation on the dt setting.    

Thanks!  R

[Christen Fleming]

Hi Robin,

There is some information in vignette('variogram') https://ctmm-initiative.github.io/ctmm/articles/variogram.html#irregular-sampling-schedules

and also in an appendix of the cited reference:

C. H. Fleming, J. M. Calabrese, T. Mueller, K.A. Olson, P. Leimgruber, W. F. Fagan, “From fine-scale foraging to home ranges: A semi-variance approach to identifying movement modes across spatiotemporal scales”, The American Naturalist, 183:5, E154-E167 (2014) doi:10.1086/675504.

If there is any other information needed, then please let me know.

Best,

Chris