abundance.est in dsm model

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olga30dec

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Jul 14, 2021, 9:55:45 AMJul 14
to distance-sampling
Dear all, 

I am struggling to understand how to access response variable abundance.est in dsm model. At the moment I am fitting  family = quasipoisson(link = "log")
However model diagnostics shows that this distribution family does not fit well.
I tried to fit gamma but I get error: Non-Positive values not allowed for the gamma. 
Where do I get  non positive values from? I am trying to inspect my response variable, but I cannot find the way to access it.

Many thanks for your help,
Olga

Eric Rexstad

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Jul 14, 2021, 10:03:42 AMJul 14
to olga30dec, distance-sampling

Olga

The short answer to your question regarding the error arising from trying to fit a gamma is that 0 is a non-positive value.  Therefore segments without detections will have 0 as the abundance; the gamma does not like this.

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Olga Lyashevska

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Jul 15, 2021, 4:35:07 AMJul 15
to distance-sampling
Thank you very much Eric for this clarification. This makes sense. What distribution within dsm (or mgcv) can deal with zero-inflation? Segmentation introduces zeros, the number of which which depend on the size of segments. The only option I see is zero-inflated Poisson, however adundance.est is not count. What would be the best way to address this?  Thanks for your help! 

Eric Rexstad

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Jul 18, 2021, 6:26:18 AMJul 18
to Olga Lyashevska, distance-sampling
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