Ecological Archives A017-081-A1

Jonathan M. Hoekstra, Krista K. Bartz, Mary H. Ruckelshaus, Jennifer M. Moslemi, and Tamara K. Harms. 2007. Quantitative threat analysis for management of an imperiled species: Chinook salmon (Oncorhynchus tshawytscha). Ecological Applications 17:2061–2073.

Appendix A. Supplemental methods.

Following Burnham and Anderson (2002), model-averaged estimates of effects () for each confidence set were calculated as:


where  was the maximum likelihood estimate of an effect from model i (or zero if the associated effect was excluded from the model variation) and  was the Akaike weight of model i. Model-averaged variance estimates () also were calculated:


where  was the Akaike weight of model i,  was the bootstrap-derived estimate of variance about the maximum-likelihood estimate of  from model , and  was the model-averaged estimate of the parameter of interest. If an effect was excluded from model ,  and  were fixed to zero. This formulation for estimating model-averaged variance included a component reflecting model selection uncertainty and thus was not conditioned on any single model in the confidence set.

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