Design Verification & Validation

flight-sky-earth-spaceThis chapter will introduce the key concept of Design Verification & Validation including the definitions, standards, processes, deliverables & best practices associated with this important Design Activity.

I’ll start by covering the difference between Design Validation & Design Verification and then quickly discuss a handful of the Quality Standards that provide guidance for Design Validation.

From there we move into the nuts and bolts of executing a Design Validation with some of generally accepted best practices surrounding the Design V&V Process.

Next, we touch two of the common Statistical Tools that you can utilize during Design Validation. Finally we discuss the relationship between Design V&V and Process Validation.

Design Verification & Validation

One of the first things you need to know about Design V&V (Verification & Validation) is the difference between Verification & Validation. This Distinction is important because these activities are meant to accomplish different goals, however they are often intertwined together and confused.

The Difference between Design Validation & Design Verification

Design Validation means confirmation by examination & evaluation of objective evidence to confirm that your final product meets the customer’s needs & intended use.

Design Verification means confirmation by examination and evaluation of objective evidence that your Design Output (Product Specification & Requirements) meets all your Design Inputs (Technical Reflection of Customer Needs).

Design V & V Waterfall

Design Validation can be expressed by the question “Are You Building the Right Thing” and Design Verification is expressed by the question “Are you building it right?

Building the right thing is all about meeting the customer’s needs while building it right confirms that your product specifications have been implemented & cascaded into your quality system such that your process & it’s output (final product) meets all of the technical & functional specifications as well as the customer’s needs.

Quality Standards for Design Verification & Validation

The definitions above are a direct reflection of the Quality Standards that govern Design Validation & Verification.

For example, ISO 9001:2015 contains two definitions in Section 8.3.4 (Design & Development Control).

It starts in section 8.3.4.C which says that Verification activities are conducted to ensure that the design & development output meets the input requirements (functional requirements & specifications).

Next the standard says in 8.3.4.D says that Validation activities are conducted to ensure that the resulting products and services meet the requirements for the specified application or intended use (Customer Needs).

The FDA has two similar sounding requirements in their Code of Federal Regulation (CFR) Part 820, Quality System Regulation (QSR).

The CFR starts by defining the requirement for Design Verification in 21 CFR 820.30 (f) by saying – Design verification shall confirm that the design output meets the design input requirements.

In the very next breath, they move on to define the requirement for Design Validation in 21 CFR 820.30 (g) by saying – 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.

The CFR also has specific requirements for Design Validation which include both include the need for a procedure to govern these activities, as well as documented evidence of completion.

Customer needs in ValidationDesign Validation Testing

Another important requirement for Design Validation that also comes out of the Standards is the requirement that testing be performed under defined operations conditions – under actual or simulated use conditions, using initial production units.

Some Industry Standards for Validation say that you should challenge the extremes of “Customer Usage” conditions and should attempt to capture as much variation within the production process as possible.

This would also include testing at the maximum environmental & aging conditions (shelf life) that are allowed.

The essence of this requirement can be summed up by that key word – variation. Your product will be exposed to many different sources of variation throughout its lifecycle and to properly validate your design you should attempt to capture as much of that variation in your validation activities as possible.

Executing Your Design Verification or Design Validation

Similar to Process Validation, every Design Verification or Design Validation exercise should begin with the creation of a protocol. This protocol will go on to define the scope, activities, test methods, acceptance criteria, data analysis and other factors that will be considered during validation (or verification).

For Design Verification, this might include a listing of all of the products Design Inputs (Requirements & Specifications) that must be met during the Verification exercise.

For Design Validation, this would be a list of all of your products User Needs & Intended Use (Validation). From here, you would execute all necessary testing and data analysis to complete your protocol. This information is summarized in a Final Report.

For complex products that contain many different Requirements & Specifications, this many often times result in a Requirements Traceability Matrix that links all of the Design Inputs (Product Specifications) & Customer Needs with the Verification Reports & Validation Reports that collectively proves that the product conforms to all of the stated requirements.

Statistical Methods Tools for Design V&V

While there are no hard & fast rules for using Statistical Methods in validation, many different regulations say that you must provide your rationale for the statistical techniques that you choose, which is stated in the FDA’s CFR Section 820.250.

In general there are two primary statistical methods that are used during Design V&V to show conformance of your product to all of the requirements & customer’s needs.

The first are Sampling Plans if used properly, they allow you to make certain claims about the capability of your product to meet the specification with a given confidence level, usually 95% or 99%.

So for example, if you select the proper sampling plan and acceptance criteria, you can make a claim such as: “With 95% confidence, we can say that 99% of the product meets specifications.”

The next statistical method is Hypothesis Testing which, depending on your product requirements, can be used to compare the product your validating against a desired result (Functional Requirement) to show that, with a particular level of confidence, your product is performing at a particular level.

Design Validation v. Process Validation

There are often many questions about Design Validation and its relationship with process validation, especially in terms of timing of the two activities.

As I mentioned before, many industry standards require that Design Validation be conducted using initial production units, which implies that your process should likely be validated or at least very least you have conducted a portion of your process validation activities (IQ/OQ/PQ) prior to design validation.

On the flip side of that, some Process Development Experts often times like to wait until the Design Validation is successful before completing their Process Validation.

That way if the design validation fails in such a way that the product itself has to change, it would likely result in a process change which would require that the process development engineer redo his process validation.

So it’s a bit of chicken and an egg situation, but the point is that Design Validation and Process Validation may be two separate activities but they are inexplicably linked together in development through Design Transfer.

You’ll also see many Process Validation experts talking about a Product PQ (Performance Qualification). This is essentially equivalent to a Design Validation or Verification. This Product PQ is the portion of validation where you assure that the product that is coming off the end of your production line meets the product specification & customer needs.

This is where Design V&V can actually support Process Validation because it fulfills the requirements for a Product PQ during Process Validation.

Excellent Quality & Design ValidationConclusion

In summary, this chapter introduced the concept of Design Verification & Validation and definitions, standards, processes, deliverables & best practices associated with this important Design Activity.

Real quick, those definitions for Design Validation & Design Verification are below:

Design Validation means confirmation by examination & evaluation of objective evidence to confirm that your final product meets the customer’s needs & intended use.

Design Verification means confirmation by examination and evaluation of objective evidence that your Design Output (Product Specification & Requirements) meets all your Design Inputs (Technical Reflection of Customer Needs).

Design Validation can be expressed by the question “Are You Building the Right Thing” and Design Verification is expressed by the question “Are you building it right?

From there we quickly touched on a few of the Quality Standards that provide guidance on Design Validation – these include ISO 9001 & the Code of Federal Regulations.

These industry standards led us into our next discussion regarding the execution of your design validation which normally requires that you challenge the extremes of “Customer Usage” conditions and should attempt to capture as much variation within the production process as possible.

This would also include testing at the maximum environmental & aging conditions (shelf life) that are allowed. This ensures that your validation activities are robust and would apply to any potential situation where your customer may reasonably use your product.

Next we discussed the usage of a protocol during Design V&V to define the scope, activities, test methods, acceptance criteria, data analysis and other factors that will be considered during validation (or verification).

From here, you would execute all necessary testing and data analysis to complete your protocol. This might include the usage of some common Statistical Methods used in Validation, including a valid sampling plan or hypothesis testing.

This data and analysis is then summarized in a Final Report to complete your Design Validation activities.

Lastly we discussed the relationship between Design Validation and Process Validation in terms of your overall Validation Plan. The next chapter will cover Process Validation and all of the definitions, standards, processes, deliverables & best practices associated with this activity.

Practice Quiz

Design Verification & Validation

This quiz covers the Design Verification & Validation chapter of the Product & Process Design pillar.

NEXT: Process Validation