TMV Fundamentals
A test method reports a numerical measurement such as length, force, or pressure. Is it generally Attribute or Variable?
Variable. A variable test method produces numerical results referenced to a continuous scale.
What document should you use to determine the number of nonconforming trials needed for an ATMV sampling plan?
90030419 Global WI Sampling Plan.
Does the addition of a new UPN automatically require a new ATMV or VTMV?
No. Both ATMV and VTMV WIs clarify that “product/part” is not synonymous with an individual UPN; representativeness of the test articles is the key consideration.
An existing ATMV has five validated defect types and a new sixth defect type is added. What validation pathway should you consider?
Augmented Test Method Validation.
Can previously collected data ever be used to support a VTMV instead of generating all-new data?
Yes, provided the existing-data requirements are satisfied.
Name the four statistical methods identified in the VTMV WI.
Guardband Analysis, Gage R&R, Power/Sample Size Analysis, and Capability Analysis.
For an ATMV containing defect types with several different Risk Index values, which Risk Index is used to establish the minimum confidence/reliability requirement?
Use the highest Risk Index represented in that test.
For ATMV leveraging, must the new application use the same equipment, or is merely “equivalent” equipment sufficient under the current WI criteria?
The current criteria specify the same equipment. Rev I tightened the previous “same or equivalent” wording.
When running an Augmented ATMV, can several new defect types be combined into one multiple-defect validation?
No. An augmented ATMV uses the Single Defect Type validation approach.
Name two requirements historical VTMV data must meet before they can be used.
acceptable answers: controlled storage/full traceability; within the validated range and representative of intended use; adequate sample size unless an SME approves an exception.
Where should you look for the actual VTMV acceptance criteria rather than the instructions for executing the study?
97045437 Global SOP Variable Test Method Validation. The VTMV WI directs users there for the acceptance criteria.
ATMV testing normally requires at least how many inspectors, and how many are recommended?
Minimum two; at least three recommended, except as otherwise addressed for automated systems.
An existing Gage R&R covers several UPNs. A new UPN has the same characteristic and equipment but a tighter tolerance. What should you consider before repeating the study?
Re-evaluate the existing Gage R&R results against the new/tighter specification and determine whether current acceptance criteria are still met.
A VTMV measures the same characteristic as before, but a new EDO tightens its specification. Is an entirely new physical Gage R&R always required?
No. The change must be evaluated to determine the extent of revalidation; existing data may support re-analysis if appropriate.
A historical Gage R&R dataset contains only four distinct numerical values. What current VTMV concern does this raise?
Gage R&R data must contain at least five distinct numerical values; fewer values may indicate inadequate resolution or insufficient part variation.
A test method compares the means of two populations rather than accepting/rejecting individual units. What type of VTMV method is Power/Sample Size Analysis intended to support?
A comparative test method used to compare population means, such as with a t-test or ANOVA.
When pooling several products/parts into one VTMV analysis, what two conditions must be considered for the pooling approach described in the WI?
The products/parts should have the same tolerance, and their test-method variation must reasonably be assumed comparable.
A VTMV was validated by Capability Analysis. A truly new product/part is introduced. Can the prior Capability Analysis be leveraged as the new product’s validation?
No. Capability Analysis and Power/Sample Size Analysis are not leverageable validation methods for new products/parts/components; a new TMV report is required.
A revised attribute EDO changes the visual boundary between acceptable and unacceptable product. What should happen before assuming the old ATMV still covers it?
Assess the impact of the changed attribute requirement, update the applicable controlled instructions/documents, establish new acceptance criteria, and perform validation/revalidation as applicable.
For a VTMV with a one-sided specification, what limitation applies if you use a historical mean in the %P/T calculation?
The historical mean must come from a valid data source; alternatively the Gage R&R study average may be used only when representative of the nominal output mean.
A team argues: “The test method is already validated, so any product using the same procedure is covered.” What major principle in the updated WIs makes that statement incomplete?
Validation must be representative of the specific intended use/test articles and measurement system. Same procedure alone does not establish that product characteristics, range, equipment, fixtures, tolerances, etc. are represented.
You are designing a VTMV across several product variants. Name the three general approaches the WI permits for selecting representative products/parts.
Worst-case/challenging product, bracketing, or pooling different products/parts into one analysis when appropriate.
A new UPN uses the same measured characteristic and calibrated gage, but its softer material may deform in the fixture. Can it simply be added under the old Gage R&R because the UPN is part of the same product family?
Not automatically. Material, size, shape, texture, durometer, and similar characteristics must either be the same or shown not to affect test-method performance.
A new product or component is added to an existing VTMV, rather than merely changing the tolerance of an already validated characteristic. What is the key question when deciding whether the old VTMV can cover it?
Whether the product/component characteristic is the same and would not impact TM performance. Also whether the existing measurement-system validation is representative of the new intended use. Also if the leveraged TM validation meets the current acceptance criteria requirements.
Data come from a “very similar” historical method and meet sample-size requirements. What must still be established before treating those data as valid support for the current TMV?
You still must establish that the historical data are from a measurement system/application that legitimately represents the validated range and intended use, with controlled traceability and appropriate current acceptance-criteria analysis. “Similar” alone is not sufficient.