Table 2.

Passing-Bablok correlation parameters

	Passing-Bablok regression equation	95% CI of the intercept	95% CI of the slope	Cusum test for linearity	Spearman correlation coefficient (significance)
R1 vs. R2	y = − 41.00 + 1.54x	− 68.98; − 11.30	1.46–1.61	N.S. deviation from linearity (p = 0.991)	0.972 (p < 0.001)
R1 vs. LC-MS/MS	y = − 60.07 + 1.52x	− 98.60; − 24.53	1.43–1.62	N.S. deviation from linearity (p = 0.635)	0.960 (p < 0.001)
R2 vs. LC-MS/MS	y = − 11.39 + 0.99x	− 28.23; − 0.42	0.96–1.03	N.S. deviation from linearity (p = 0.459)	0.973 (p < 0.001)

R1, Roche I; R2, Roche II cortisol assay; LC-MS/MS, liquid chromatography tandem mass spectrometry