Table 3.

Relationship between hair cortisol concentrations (HCC) measured by enzyme immunoassay (EIA) kit 1 and kit 2 by Oxford Biomedical Research (Oxford, Michigan, USA) in all samples, males only, females only. Model performance was assessed by over and under estimation of test samples, mean (±SD) predicted percent error (PE; (((|actual value – predicted value|)/actual value) × 100)), percent of samples with a PE<20%, and comparison of predicted values and actual matched concentrations using the Wilcoxon's signed-rank test. These EIA kits were used to measure cortisol concentration in the hair of brown bears (Ursus arctos) collected from free-ranging populations in Sweden and Alberta, Canada from 1996–2013.

Data	Equation	R2	%over	%under	%PE	%<20%PE	Wilcoxon's signed-rank test (median HCC pg/mg)
All (n = 86)	kit2=(0.98 x kit1)+1.65	0.85	62	38	16±15	72	predicted=3.87; actual=3.52; p = 0.29
Male (n = 44)	kit2=(1.05 x kit1)+1.22	0.85	40	60	14±11	67	predicted=2.93; actual=3.30; p = 0.13
Female (n = 42)	kit2=(0.89 x kit1)+1.98	0.89	57	43	13±10	93	predicted=4.25; actual=4.59; p = 0.95