What is the first step in method evaluation?

• A. Precision study
• B. Linearity assessment
• C. Accuracy assessment
• D. Robustness testing

Answer: (A)

Establishing how consistently a method measures the same sample (precision) is the first step in method evaluation. Precision evaluates random error and shows how repeatable the results are under the same conditions (repeatability) and across minor changes like different days or operators (intermediate precision). By testing multiple replicates of a sample and calculating the variation (often expressed as the coefficient of variation), you get a baseline picture of the method’s stability.

Why this comes first: if a method isn’t precise, its results are inherently noisy, making it impossible to judge other performance aspects like accuracy (how close measurements are to the true value) or linearity (response across the measurement range). Once precision is demonstrated to be acceptable, you can meaningfully assess accuracy, then linearity, then robustness, in a logical sequence.