Measurement literacy
“Not detected” is a result that still needs context
Pro Pep Source Editorial · · 2 min read
Editorial dates use America/Chicago.
Two short words can hide a long analytical story. “Not detected” is easy to read as a complete absence statement, especially when a report has little space for explanation. A careful reader asks what the laboratory searched for and how the method’s reporting convention was applied.
Prepared with AI assistance for Pro Pep Source Editorial. These educational explanations have not undergone independent scientific peer review.
Distinguish the reporting categories
ICH Q2(R2) distinguishes detection and quantitation limits. Detection concerns whether an analyte can be detected, while quantitation concerns measurement with suitable accuracy and precision. Those are different questions; a report should make clear which type of limit is relevant.
When reading a result, keep the analyte name, unit, stated limit, and reporting term together. If the report uses an abbreviation, look for its definition. Do not assume that two laboratories use the same abbreviation in the same way without checking their documentation.
Keep the sample context attached
Ask whether the reporting convention applies to the submitted sample and the preparation actually used. The method identifier and version are important here, as is any qualification stated by the analyst. A detached result copied into a spreadsheet can lose exactly the note that makes it interpretable.
A useful review preserves the original wording and adds a question when needed: “Which limit does this statement refer to?” or “Where is the reporting convention defined?” These questions invite clarification without inventing an experimental value or reinterpreting an unseen analytical run.
Write an appropriately bounded conclusion
Measurement language should communicate its limits. NIST’s uncertainty guidance is a useful reminder to read the explanation accompanying a result rather than treating the printed number as the entire measurement. The same reading discipline helps with qualitative reporting terms.
For a research summary, say what was reported under the cited procedure. Avoid rewriting “not detected” as “zero,” and avoid adding claims about untested substances. If the question requires different evidence, identify that need explicitly. This article provides no sample findings and should not be used to fill gaps in a real report.
Primary sources & editorial scope
The explanations and review questions are original editorial commentary. FDA RUO guidance concerns IVD products; ICH Q2 and Q14 address pharmaceutical analytical procedures. Citations do not assert regulatory approval or guideline compliance for research materials.