blind sample

**Blind Sample** is a **quality control sample whose true value is unknown to the analyst or operator performing the measurement** — the sample is submitted without identification or expected results, eliminating any conscious or unconscious bias in the measurement or data interpretation. **Blind Sample Protocol** - **Preparation**: A quality manager or independent party prepares the blind sample — the analyst doesn't know it's a QC sample. - **Submission**: The blind sample is submitted as a routine sample — measured using standard procedures. - **Evaluation**: After measurement, the result is compared to the known value — assesses the measurement system under real conditions. - **Double Blind**: Neither the analyst NOR supervisor knows which samples are blind — maximum objectivity. **Why It Matters** - **Bias Prevention**: Operators may unconsciously adjust measurements when they know the expected result — blind samples reveal true performance. - **Realism**: Blind samples test the entire measurement process — sample handling, measurement, and data reporting. - **Regulatory**: Some quality systems require blind sample testing — FDA GMP, ISO 17025, clinical laboratories. **Blind Sample** is **the honest test** — measuring a sample without knowing the expected answer to evaluate true measurement performance without bias.