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Hi All, I'm currently in the process of running ZIP models in rjags to test some hypotheses about duck pair abundance. The zero-inflated models include only an intercept parameter and then 3 different dummy parameters to represent the wetland cover class variables 2, 3, and 4. In theory, one would expect the non-transformed value of the parameter estimates to decrease in value from cover class 1 to 4 sequentially. I'm seeing this trend in the MLE models we ran first actually: (Intercept) WCCone WCCthree WCCtwo -6.4537 6.0062 0.8016 3.5753 Unfortunately, I'm running up against a bit of a snag in rjags. The parameter estimates for the wetland cover classes in the zero-inflated portion of the model all end up being relatively the same (~-7 - -8) and are truncated at -10 (see the not-so-nice looking trace plots in attached word file: a2,a3,a4). I've checked for correlations among the covariates, mistakes in the data, and at this point, I am concerned that this might be a coding problem. I realize this is somewhat of an inane question to ask, however, I'm unfortunately not in an academic lab where I can easily find a fellow JAGS coder, so usually end up having to turn to sources like these if I want a second set of eyes. So, I'm hoping there's someone out there who is willing to look through the attached code and let me know if they see an error that might be causing these weird results. I've literally spent the last 6 months digging through these data and this code so I think my eyes cross every time I look at it. Any help would be great. Thanks, KC Example.docx KCScript.R
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Instructors: Marc Kéry & Jérôme Guélat, Swiss Ornithological Institute Date: 9–11 February 2015 Venue: Universidade Federal de Viçosa, Minas Gerais, Brazil Computers: Bring your own laptop with latest R, JAGS and WinBUGS or OpenBUGS Costs: 1000 Reais (400 US$) This course gives an introduction to Bayesian statistical modeling using BUGS software and then introduces a key class of models for the analysis of species distribution, habitat selection, occurrence and abundance: site‐occupancy models (MacKenzie et al. 2002, 2003; Tyre et al. 2003). Model fitting is shown using the Bayesian BUGS software and the R package unmarked. The course follows the book “Bayesian population analysis using WinBUGS” (Academic Press, 2012) by Kéry & Schaub and the upcoming book “Applied hierarchical models in ecology” (Academic Press, 2015) by Marc Kéry & Andy Royle. See the attached flier for more details. Occupancy Workshop Announcement, Vicosa, 9-11 Feb 2015.pdf
