{"id":"wpc-tech100-article-089-en","slug":"outliers-in-wpc-testing-investigate-before-excluding","locale":"en","url":"https://woodplasticcomposite.net/guides/outliers-in-wpc-testing-investigate-before-excluding/","title":"Outliers in WPC testing: investigate before excluding","answer":"An unusual result should prompt an investigation, not automatic deletion. It may reveal a preparation error, a measurement problem or genuine material variation relevant to production.","author":"NFC & WPC Knowledge Reference","faqIds":["wpc-tech100-faq-089-en"],"tagIds":[],"noindex":false,"related":["wpc-tech100-article-090-en"],"version":1,"modified":"2026-10-15","reviewer":"","sections":[{"id":"technical-context","text":"Removing a low result because it looks inconvenient biases the reported performance. Conversely, a documented equipment malfunction may justify excluding a measurement under the agreed method. The decision needs evidence and a consistent rule.","heading":"Technical context","references":[],"url":"https://woodplasticcomposite.net/guides/outliers-in-wpc-testing-investigate-before-excluding/#technical-context"},{"id":"verification-plan","text":"Retain raw results and record the reason for any exclusion. Review specimen identity, conditioning, test setup and failure observations. Where a retest is justified, state whether the original result remains part of the report and why.","heading":"What to measure and document","references":[],"url":"https://woodplasticcomposite.net/guides/outliers-in-wpc-testing-investigate-before-excluding/#verification-plan"},{"id":"practical-decision","text":"A credible technical file shows how uncertainty was handled. For buyers, unexplained perfect consistency can be less informative than a transparent account of variation. The objective is an honest estimate of performance, not the most flattering average.","heading":"Implications for development and specification","references":[],"url":"https://woodplasticcomposite.net/guides/outliers-in-wpc-testing-investigate-before-excluding/#practical-decision"},{"id":"reading-scope","text":"General engineering-statistics guidance; not a WPC product standard. Use the linked work as related reading. The practical checks above are editorial recommendations, not reported test results or a substitute for product qualification.","heading":"Related reading and evidence limits","references":[1],"url":"https://woodplasticcomposite.net/guides/outliers-in-wpc-testing-investigate-before-excluding/#reading-scope"}],"seoTitle":"Outliers in WPC testing: investigate before excluding | WPC Reference","topicIds":[],"published":"2026-10-15","tableText":"Review step | Evidence to retain\nMaterial and geometry | Exact specimen or product identity\nVerification | Method, conditions and individual observations\nDecision | Approved scope and documented limitations","takeaways":"Removing a low result because it looks inconvenient biases the reported performance.\nRetain raw results and record the reason for any exclusion.\nA credible technical file shows how uncertainty was handled.","aiAssisted":true,"categoryId":"wpc-tech100-category-4","reviewedAt":"","change_note":"New focused technical draft; not a product certification or production recipe.","description":"An unusual result should prompt an investigation, not automatic deletion.","heroImageId":"","referenceIds":["wpc-tech100-ref-statistics"],"review_status":"AI-assisted English editorial draft. Human technical review has not been recorded.","table_caption":"Evidence checklist for outliers in wpc testing: investigate before excluding","seoDescription":"An unusual result should prompt an investigation, not automatic deletion.","translationGroup":"wpc-tech100-089-2026","references":[{"url":"https://www.itl.nist.gov/div898/handbook/","type":"web","title":"NIST engineering statistics handbook","noindex":false,"accessed":"2026-10-14","seoTitle":"NIST engineering statistics handbook","publisher":"NIST","description":"Related reading; scope and limitations are identified in each article.","seoDescription":"Related reading; scope and limitations are identified in each article."}],"faqs":[{"question":"What evidence is needed for outliers in WPC testing: investigate before excluding?","answer":"Retain raw results and record the reason for any exclusion. Review specimen identity, conditioning, test setup and failure observations. Where a retest is justified, state whether the original result remains part of the report and why."}]}