{"id":"wpc-tech100-article-084-en","slug":"repeatability-and-reproducibility-in-wpc-laboratories","locale":"en","url":"https://woodplasticcomposite.net/guides/repeatability-and-reproducibility-in-wpc-laboratories/","title":"Repeatability and reproducibility in WPC laboratories","answer":"Repeated testing by one operator and testing across operators or laboratories address different sources of variation. WPC development benefits from distinguishing them before ranking small performance differences.","author":"NFC & WPC Knowledge Reference","faqIds":["wpc-tech100-faq-084-en"],"tagIds":[],"noindex":false,"related":["wpc-tech100-article-085-en"],"version":1,"modified":"2026-10-15","reviewer":"","sections":[{"id":"technical-context","text":"A narrow spread within one test series does not establish that another laboratory will obtain the same result. Preparation, conditioning and equipment interpretation can introduce differences even when the nominal method name is identical.","heading":"Technical context","references":[],"url":"https://woodplasticcomposite.net/guides/repeatability-and-reproducibility-in-wpc-laboratories/#technical-context"},{"id":"verification-plan","text":"Use a planned comparison with traceable specimens and agreed procedures. Examine the measurement system before concluding that a small formulation change caused a real improvement. Retain individual results and observations instead of circulating averages alone.","heading":"What to measure and document","references":[],"url":"https://woodplasticcomposite.net/guides/repeatability-and-reproducibility-in-wpc-laboratories/#verification-plan"},{"id":"practical-decision","text":"When comparing supplier reports, check compatibility of methods and specimen states. If a decision turns on a small difference, request a controlled comparison. Laboratory precision is valuable, but it should not be confused with proof of a large practical advantage.","heading":"Implications for development and specification","references":[],"url":"https://woodplasticcomposite.net/guides/repeatability-and-reproducibility-in-wpc-laboratories/#practical-decision"},{"id":"reading-scope","text":"Official guidance on controlling measurement processes and supporting uncertainty statements. 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/repeatability-and-reproducibility-in-wpc-laboratories/#reading-scope"}],"seoTitle":"Repeatability and reproducibility in WPC laboratories | 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":"A narrow spread within one test series does not establish that another laboratory will obtain the same result.\nUse a planned comparison with traceable specimens and agreed procedures.\nWhen comparing supplier reports, check compatibility of methods and specimen states.","aiAssisted":true,"categoryId":"wpc-tech100-category-4","reviewedAt":"","change_note":"New focused technical draft; not a product certification or production recipe.","description":"Repeated testing by one operator and testing across operators or laboratories address different sources of variation.","heroImageId":"","referenceIds":["wpc-tech100-ref-measurement"],"review_status":"AI-assisted English editorial draft. Human technical review has not been recorded.","table_caption":"Evidence checklist for repeatability and reproducibility in wpc laboratories","seoDescription":"Repeated testing by one operator and testing across operators or laboratories address different sources of variation.","translationGroup":"wpc-tech100-084-2026","references":[{"url":"https://www.itl.nist.gov/div898/handbook/mpc/section2/mpc2.htm","type":"web","title":"NIST: statistical control of measurement processes","noindex":false,"accessed":"2026-10-14","seoTitle":"NIST: statistical control of measurement processes","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 repeatability and reproducibility in WPC laboratories?","answer":"Use a planned comparison with traceable specimens and agreed procedures. Examine the measurement system before concluding that a small formulation change caused a real improvement. Retain individual results and observations instead of circulating averages alone."}]}