Fig. 2.

A Bland–Altman plot (difference plot) was used to analyze the agreement between hair cortisol concentrations (HCC) measured by enzyme immunoassay (EIA) kit 1 and kit 2 by Oxford Biomedical Research (Oxford, Michigan, USA). The solid black line is the mean HCC using kit 1 and kit 2. The dashed blue lines represent the 95% limits of agreement for each comparison (mean difference ± 1.96 standard deviation of the difference). Samples that fell outside of the 95% limits of agreement were removed from further analysis (n = 25) and the remaining samples (n = 86) were used to determine the linear relationship between the two kits. 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.