First check the tested sample, test method, limit and units, then ask the laboratory to explain the applicable decision rule and measurement uncertainty. If the rule, the scope represented by the sample or report information remains unconfirmed, mark the corresponding decision as pending. Do not release an entire lot solely because a result is just below or above a number, and do not rewrite an agreed decision rule yourself. Agreeing before testing what the report must answer, who decides and how borderline results are handled is more useful than arguing after the report arrives.
This guide addresses numerical results where uncertainty must be considered in the conformity decision, helping buyers communicate with laboratories. Not every knitwear check expresses uncertainty in the same way; colour grades, visual inspection and other items require their own applicable methods and decision requirements. A contract, customer specification or regulation may already prescribe a rule. The assumptions here cannot replace those requirements and do not establish conformity for any particular goods.
Separate the result, limit, decision rule and release
The measurement result describes the value actually measured and reported. A limit is the requirement for the characteristic being assessed; it may be an upper limit, a lower limit or an interval. Record its unit, direction, version and scope. Uncertainty describes uncertainty associated with the measurement result. Ask the laboratory to explain its value, expression and coverage; it is not simply an error or a universal tolerance that a buyer can add or subtract.
NIST's definition of a decision rule explains that the rule describes how measurement uncertainty is considered in a statement of conformity. NIST research on conformity and risk distinguishes the specification's conformity zone from the result acceptance zone and discusses the risks of wrongly accepting or wrongly rejecting. The applicable rule depends on actual requirements and agreements; a general webpage does not automatically determine the rule for this order.
A laboratory's conformity statement for an agreed item and scope is a different decision from the buyer authorizing shipment. Shipment may also require checks of quantity, identification, other tests and unresolved issues; one conforming report item cannot replace those checks. The knitwear conditioning and report guide focuses on sample preparation and test environment; this guide goes further into decisions when a result is close to a limit.
A checklist for the decision information
| Item | What to record | If unclear |
|---|---|---|
| Sample identity and scope | Style, colour, size, location, lot, preparation and sampler | Confirm the report's relationship to the goods; do not extend its conclusion |
| Method and result | Item, method version, measured value, unit, reporting precision and deviations | Ask the laboratory to clarify; do not replace the result yourself |
| Applicable requirement | Limit, upper or lower direction, unit, source and version | Have the responsible party confirm the actual requirement |
| Uncertainty and rule | Laboratory's expression, coverage information and how it is used for a conformity statement | Ask whether a prescribed or written rule exists; keep the decision pending |
| Decision and responsibility | Laboratory statement, buyer's next action, affected goods and decision maker | Identify the pending scope, next step and deadline |
This is a communication checklist, not a mandatory laboratory report template. Report format, whether and how uncertainty and statements are supplied depend on the commission, applicable requirements and laboratory explanation. Do not assume a missing field proves the test invalid, and do not pretend a decision has been made when information is insufficient.
Use hypothetical figures to understand two different rules
Suppose, solely for illustration, an order sets an upper limit of 5.0% shrinkage for a dimensional-change test. The reported result is 4.8%, and the laboratory gives an expanded uncertainty of 0.4 percentage points. Assume the figures share the same definition, method and units, and that this example's agreed rule compares the reported result with the upper limit: 4.8% does not exceed 5.0%, so a conformity statement can be made under that hypothetical rule. This is not a conclusion about an actual order.
Now suppose another rule sets the acceptance limit at the upper limit minus 0.4 percentage points and requires the result not to exceed that acceptance limit. The acceptance limit is then 5.0% − 0.4 percentage points = 4.6%; 4.8% is above 4.6%, so an acceptance decision cannot be made under that hypothetical rule. The 0.4 is in percentage points; it does not mean multiplying 5.0% by 0.4%. The same result may receive different decisions under these two rules. The example does not require either rule or establish that any actual method has an uncertainty of 0.4 percentage points.
The interval calculated from the example is 4.4% to 5.2%, but it is not a guarantee for every bulk garment, and its coverage meaning should not be interpreted without the laboratory's explanation. Rules may have other conditions; follow applicable regulations or customer specifications where they prescribe requirements. Ask the laboratory and responsible parties to explain the selected rule, actual calculation, boundary treatment and statement wording rather than choosing a more favourable rule after seeing the result.
What to do when a result is borderline
Keep the complete original report and applicable specification. Check specimen source, colour and size, location, production lot, prior treatment and method version. Confirm that the measured value, unit, limit, reported uncertainty and laboratory statement concern the same item and scope. If the result or rule is unclear, request a written explanation. Where necessary, ask a qualified person whether further information or retesting is appropriate and agree the new sample source, method, cost, timing and interpretation of multiple results first. Do not retest indefinitely and retain only a favourable report.
If the submitted sample cannot be shown to represent certain goods, mark those goods as outside the evidenced scope rather than extending the borderline result to the whole order. Record other unresolved testing or safety requirements separately. Acceptance sampling is a separate process for making a lot decision from a sample; the pre-shipment acceptance sampling guide explains its scope. It cannot automatically replace the laboratory item's decision rule.
Agree before commissioning and retain order records
Define the characteristic and purpose, applicable method and version, source of the requirement and limit, sample quantity and sampling locations. Confirm with the laboratory what result, uncertainty information and conformity statement it can provide, and when a customer or responsible authority must specify the rule. If a rule is already prescribed, do not choose a conflicting one. Put the final rule, report scope, approver, exception handling and responsibility for review after changes into controlled records. If material, lot, treatment or requirements change, first decide whether the original report remains applicable.
Allow time for communication: additional samples or laboratory explanations may affect decision timing, but costs and schedule need separate confirmation. Keep original results, clarifications, later reports and the final decision. Record the laboratory's testing decision, the buyer's disposition of the relevant goods and other shipment checks separately.
What to provide in an inquiry
Send WTBF an inquiry with a design or garment sample, yarn and construction, colours and sizes, quantities by style, colour and size, target markets, intended test characteristics and sources of requirements, existing reports, relevant lots and desired arrival date. Explain which samples, reports or third-party cooperation are needed and which limits and rules remain open. Ask the supplier and laboratory separately to confirm available information, test scope, costs and timing. The WTBF pullover range can illustrate the style; actual testing and release depend on project requirements and decisions by authorized people.