Interpreting coefficients

Daniel R.

unread,

Sep 12, 2016, 11:01:00 AM9/12/16

to secr

Hello,

I am running analyses using “secr” R-package. I have a doubt and I believe it can be easily clarified.

In our first camera trap survey to estimate density, we set up some cameras with bait. We are wondering if the bait has an effect on the encounter probability. Therefore, we specified the model:

secr.fit(capthist = Site, model = list(D ~ 1, g0 ~ Bait, sigma ~ 1), mask = mask_land)

As expected, there are two estimates for g0, one for unbaited sites and another for baited sites. Specifically, my question is if the second g0 estimate is the absolute estimate value or it is the difference in relation to the first g0 estimate. (Please, find model output attached).

Many thanks in advance!

Regards

model_output.txt

Murray Efford

unread,

Sep 12, 2016, 1:44:32 PM9/12/16

to Daniel R., secr

Hi Daniel

I think you're referring to the 'beta' parameters - there the estimate for g0.Baitsim is indeed the difference (on the 'link' scale). Use predict with the newdata argument to get the separate 'real' parameter estimates with and without bait (e.g. example in ?predict.secr).

Murray

--
You received this message because you are subscribed to the Google Groups "secr" group.
To unsubscribe from this group and stop receiving emails from it, send an email to secrgroup+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Daniel Rocha

unread,

Sep 13, 2016, 4:56:32 PM9/13/16

to Murray Efford, secr

Many thanks, Murray!
Your instructions worked fine. Problem solved!
Thanks again