Table 4.

Selected bowhead−killer whale interaction model (shown in Table 3) parameter estimates fitted using the clogit function and the TwoStepCLogit function for comparison

	clogit function				TwoStepCLogit function
Variable	Coefficient	Robust SE	z	p	Coefficient	SE
SIconc	−0.119	0.243	−0.491	0.623	−0.005	0.364
Dkw	0.365	1.545	0.237	0.812	1.866	2.934
SI2conc	−0.201	0.084	−2.385	0.017	−0.171	0.079
Dsh	−3.362	0.508	−6.610	<0.0001	−3.446	0.988
SIconc:Dkw	0.014	0.038	0.385	0.700	−0.001	0.055
SI2conc:Dkw	0.023	0.012	1.898	0.057	0.019	0.011
Dkw:Dsh	0.423	0.068	6.174	<0.0001	0.445	0.138
Dedge:isice = 0	1.223	0.912	1.340	0.180	1.055	0.636
Dedge:isice = 1	2.349	0.574	4.089	<0.0001	1.880	0.916
Dkw:Dedge:isice = 0	−0.150	0.128	−1.169	0.242	−0.127	0.089
Dkw:Dedge isice = 1	−0.321	−0.073	−4.393	<0.0001	−0.254	0.121

Parameter estimates, parameter SEs, and levels of significance are comparable for both fitting methods. See Table 1 for definition of terms. z, = z-score on a standard normal distribution. Bolded p values are statistically significant.