Fig. 1. Method comparison of four carcinoembryonic antigen (CEA) immunoassays by Deming regression analysis. Results are in ng/mL. Black solid lines are from Deming regression. Black dashed lines are x=y. Comparison of CEA concentrations between ARCHITECT i2000sr and ADVIA Centaur XP (A), Elecsys E170 and ADVIA Centaur XP (B), UniCel DxI800 and ADVIA Centaur XP (C), Elecsys E170 and ARCHITECT i2000sr (D), UniCel DxI800 and ARCHITECT i2000sr (E), and UniCel DxI800 and Elecsys E170 (F).