Calculating SIF and SE from model output

questions concerning analysis/theory using program PRESENCE

Calculating SIF and SE from model output

Postby CalebBomske » Mon Jul 18, 2022 11:42 am

I recently ran a set of four two-species interaction models with competing hypotheses of dependence/independence of detection/occupancy for muskrat and mink. Using the equation provided in Richmond et al. (2010), I calculated SIF to be 1.8 from psiA, psiBA, and psiBa. The equation is:

SIF= (ψ^A ψ^BA)/(ψ^A (ψ^A ψ^BA+(1-ψ^A ) ψ^Ba))

However, the derived parameters produced by PRESENCE for specific sites average 0.76 for the same model. Why would my calculated SIF be above 1 but site-specific SIFs be below 1? Secondly, how can I calculate a SE for my calculated SIF? Or do I need to average site-specific SIFs to get a SE?
Thanks in advance,
Posts: 5
Joined: Fri Jan 21, 2022 1:57 pm

Re: Calculating SIF and SE from model output

Postby jhines » Tue Jul 19, 2022 1:54 pm

Where did you get the values for psiA, psiBA and psiBa which you used to compute the SIF of 1.8? Did they incorporate the covariates? If you send me the most recent backup zipfile from your project folder and how you computed the SIF, I think I can provide an answer.

Posts: 587
Joined: Fri May 16, 2003 9:24 am
Location: Laurel, MD, USA

Return to analysis help

Who is online

Users browsing this forum: No registered users and 1 guest