--- title: "Method Validation: Accuracy, Precision, Recovery and Robustness" description: "A method is not finished when it produces numbers. Validation is the evidence that the numbers are right, repeatable by someone else, unaffected by small changes, and correct on a sample of known cont" canonical: https://lightmysky.com/learn/science/method-validation-accuracy-precision-recovery-and-robustness-mt_ihmF2fl4OC source: https://lightmysky.com/learn/science/method-validation-accuracy-precision-recovery-and-robustness-mt_ihmF2fl4OC.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Method Validation: Accuracy, Precision, Recovery and Robustness A method is not finished when it produces numbers. Validation is the evidence that the numbers are right, repeatable by someone else, unaffected by small changes, and correct on a sample of known content. Subject: Science · Area: Chemistry · Ages 21 to 22 Page: https://lightmysky.com/learn/science/method-validation-accuracy-precision-recovery-and-robustness-mt_ihmF2fl4OC ## Ready when they can - Separates accuracy from precision and names the experiment that tests each - Designs a spike and recovery experiment and states what a recovery outside the accepted range implies - Distinguishes repeatability from reproducibility and explains why both are reported - Plans a robustness check by varying one method parameter at a time and reading the effect ## Lesson: Prove the numbers, not just make them You already know how to run a method and read a number. Validation asks whether the number deserves trust. Accuracy is closeness to the truth, tested on a sample of known content. Precision is repeatability, tested by running repeats and watching the spread. **Example.** You spike a blank sample with 10 mg and the method finds 7.8 mg, a recovery of 78 per cent. The accepted range depends on how much analyte is present: AOAC guidance expects 98 to 102 per cent for major components, widening to 80 to 110 per cent near 1 ppm. So 78 per cent fails at every level down to 1 ppm. The repeats agree closely, so the method is precise but biased. To find where the loss happens, spike one portion before extraction and one after: if only the early spike comes back low, the extraction is losing it. Repeatability means the same hands in the same lab agree. Reproducibility means a different lab agrees too. Both are reported because a method that only works for its inventor is not finished. Check robustness by varying one method parameter at a time, such as temperature or pH, and reading the effect. Small deliberate changes should barely move the result, or everyday wobble will ruin it. **Recap.** Accuracy needs known samples, precision needs repeats, other labs must agree, and small changes must not matter. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Potentiometry, Ion-Selective Electrodes and Voltammetry](https://lightmysky.com/learn/science/potentiometry-ion-selective-electrodes-and-voltammetry-mt_7sLJXqFfWR) ## Optional connections - [Calibration, the Blank and What Makes a Measurement Trustworthy](https://lightmysky.com/learn/science/calibration-the-blank-and-what-makes-a-measurement-trustworthy-mt_UNkQFonlWJ) ## Opens up - [Reading a Paper and Its Supporting Information](https://lightmysky.com/learn/science/reading-a-paper-and-its-supporting-information-mt_8t32DdAY44)