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Appendix C. Results of the sequential approach for evaluating various forms of the quantitative covariates.

Details on model selection and exploratory analysis

For the 83 models with only linear covariate forms, AIC_C values ranged from 4068 to 4667 for bison and from 3871 to 4037 for elk. The tenth smallest AIC_C values was 4079 for bison and 3883 for elk. 

For bison, the original ten AIC_C values were reduced 80–90 units using the sequential approach for evaluating various forms of the quantitative covariates the AIC_C values of the two models most supported by the data were 3974 and 3976 having Akaike model weights of w_k = 0.65 and 0.32, and with all other AIC_C > 7.6 (Table 1).

For elk, the original ten AIC_C values were reduced 12–16 units using the sequential approach for evaluating various forms of the quantitative covariates. The AIC_C values of the two models most supported by the data were 3855 and 3856 having Akaike model weights of w_k = 0.51 and 0.28, and with all other AIC_C > 2.7 (Table 2).

The following figure graphically summarizes the results of the sequential approach for evaluating various forms of the quantitative covariates. The AIC_C  values for sequence step 0 corresponds to the ten best models containing only linear forms of the covariates. In step 1, the linear form of the covariate dist is replaced with its moderated and threshold forms, while in step 2, sppnum is replaced and in step 3, cumvis or cumswe is replaced.}

FIG. C1. AICC values from sequential model assessment.