What is test Method Validation?

TMV is a risk-based arm of quality control designed to demonstrate the validity of a test or inspection method. Using TMV, the process under examination must show at various stages that it meets intended requirements and produces usable results.

how it relates with design control?

Since these tests should be run on production or production equivalent units, design validation tests are often the last tests performed. Basically, in design validation, we need to demonstrate that the product meets the user’s needs.

*I forgot the exact terminology from my previous position but I will try my best to try to explain!*

From what I have learned about Test Method Validation, through this course and my previous position, it has more to do with what methodology you are using to actually execute the test protocol. For example, one of the medical devices that I worked on had a beacon on the front face of it. The requirement that I had to test was to ensure that you could see the beacon from a distance of 6 meters away from it. The Test Method Validation that this requirement fell under was "Visual Detection"; this name stemmed from that fact that the tester needed to visually detect that he/she could in fact see the beacon light from 6 meters away from the medical device. Another Test Method Validation methodology that we also used for testing was "GUI" (Graphical User Interface). To test requirements that had this as their validation method, we would need to look at the operational portion of how the medical device worked with certain user inputs. 

I can't describe the difference between design verification vs. design verification the best way, but I did find this explanation directly from the FDA CFR 21:

Design verification. Each manufacturer shall establish and maintain procedures for verifying the device design. Design verification shall confirm that the design output meets the design input requirements. The results of the design verification, including identification of the design, method(s), the date, and the individual(s) performing the verification, shall be documented in the DHF.

Design validation. Each manufacturer shall establish and maintain procedures for validating the device design. Design validation shall be performed under defined operating conditions on initial production units, lots, or batches, or their equivalents. Design validation shall ensure that devices conform to defined user needs and intended uses and shall include testing of production units under actual or simulated use conditions. Design validation shall include software validation and risk analysis, where appropriate. The results of the design validation, including identification of the design, method(s), the date, and the individual(s) performing the validation, shall be documented in the DHF.

From my understanding, it seems like verification is done in order to validate something. Each component of a medical device needs to be verified in order for the device to be validated. TMV is used during the design verification process. 

Source:

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?FR=820.30

Test Method Validation is the process of evaluating and verifying that a testing method is capable of accurately measuring the quality or performance of a product or process. This involves establishing the accuracy, precision, repeatability, and reproducibility of the test method, and demonstrating that it can accurately detect and quantify the desired characteristics.

Test Method Validation fits within the overall design control process for medical devices, which is a series of activities aimed at ensuring that a product is safe and effective for its intended use. Design control is a critical part of the development process, and it involves a series of activities including design planning, design input, design output, design review, design verification, and design validation.

Test Method Validation is different from Design Verification/Validation in that Design Verification focuses on evaluating the design outputs to ensure that they meet the design input requirements, while Design Validation focuses on ensuring that the product is safe and effective for its intended use through testing and clinical evaluation.

Test Method Validation, on the other hand, focuses on evaluating the accuracy, precision, and reliability of the testing method itself. It is a crucial step in the design control process, as it helps to ensure that the test results are reliable and accurate and that the product will perform as intended. By validating the testing method, you can reduce the risk of false positive or false negative results, which could lead to incorrect conclusions about the product's quality or performance.

The previous replies explain the definition of test method validation quite well, but to answer your question simply on the role of TMV in design controls: test methods are developed for two main reasons in the product development world, 1. to verify design outputs meet inputs (these are the tests used in design verification) and 2. to test critical to quality characteristics of the device during manufacturing and/or upon incoming inspection. Sometimes a test method may encompass both of these reasons, but the important thing is that the test method always must be a validated test method. Therefore test method validation is an inherent part of design controls, as any test that is used for design verification or any test that will be used in the manufacturing/incoming inspection must undergo TMV.

TMV is crucial for ensuring reproducibility and consistency not just during product development, but also across different production batches and locations. A validated test method reduces variability between testers, equipment, and environments and helps to maintain compliance with regulatory standards. Also, while TMVs support design verification and manufacturing quality checks, the timing and scope can vary. During design verification, TMVs ensure that the test methods are robust enough to confirm that the design output matches input requirements. During manufacturing, TMV ensures that quality controls tests reliably detect defects and prevent faulty products from reaching the market.

Design verification is ensuring the specifications in the design specification document are met. This can be thought of making sure the individual parts of a device are as planned, as well as specifying any components being used. It also includes, if applicable, the listing of logic flowcharts such as those found for circuitry, software, and chemical processes. Design validation is ensuring the product works as intended. In other words, the device is being tested as a whole rather than its individual parts and for any effects it may have on the user. Clinical trial data and other testing methods are included in validation testing for this reason.

The Design verification and Validation test the design of your product. In an experiment, there are always statistical analysis to determine the significance of the results to prove or disprove the hypothesis. The Test Method Validation is to predict the significance of the results you’d get if you carried out the design verification/validation test procedures. If the Test Method Validation fails, that means your design verification/validation test will have no impact in determining the effectiveness of your design. Then, you would have to go back and make a new plan for Design testing. Then do the Test Method Validation, and if it passes, continue and carry out the new Design verification/validation procedures.