Method Selection, Validation, and Verification
Core concepts
Method selection balances clinical need, analytical performance, cost, and workflow. Candidates should understand analytical sensitivity, specificity, linearity, reportable range, analytical measurement range, and the limit of quantification. Validation applies to new or modified methods; verification confirms that a manufacturer's method performs as claimed in your laboratory.
Validation parameters
Know accuracy, precision (repeatability and within-laboratory), analytical specificity (interference), and reference interval verification. Understand correlation studies, recovery, and the difference between a validation and a verification plan. Recognize that commutability matters when using reference materials.
Traps in questions
- Confusing validation with verification.
- Assuming a manufacturer's claim removes the need for local verification.
- Treating linearity as identical to the reportable range.
- Ignoring interference studies when a method is changed.
Worked rule of thumb
If the laboratory adopts a method exactly as cleared by the manufacturer, perform verification; if the laboratory modifies the method or develops it in-house, perform full validation. When a question asks how many samples are needed, look for the stated regulatory minimum rather than a guess.
Study guidance
Build a table of each performance characteristic, its definition, and its acceptance criterion. Most items test whether you can match a scenario to the correct characteristic or to the correct study type.