Bias, the unfinished symphony

Area of Science:

• Laboratory medicine
• Clinical chemistry
• Biostatistics

Background:

• Mathematical equations are essential for calculating key parameters in laboratory medicine.
• Accurate calculations, like those for bias and sigma metric (SM), are vital for quality control.

Purpose of the Study:

• To evaluate the suitability of different methods for bias estimation in sigma metric (SM) calculations.
• To address a recent proposal suggesting a quadratic mean for bias calculation in SM.
• To emphasize the importance of using appropriate mathematical equations in laboratory medicine.

Main Methods:

• Analysis of bias estimation methods for sigma metric (SM) calculation.
• Critique of the arithmetic mean versus quadratic mean approach for bias calculation.
• Consideration of external quality assurance services (EQAS) data.

Main Results:

• The proposed quadratic method for bias estimation in SM calculation is not suitable.
• The arithmetic mean, while commonly used, requires careful consideration of its application.
• Incorrect mathematical approaches can lead to inaccurate quality control assessments.

Conclusions:

• Selecting the correct mathematical equation is as critical as using the right reagents in laboratory testing.
• The suitability of any mathematical equation must be rigorously checked before implementation in laboratory calculations.
• Accurate bias estimation is fundamental for reliable sigma metric (SM) performance evaluation.