Validation Methodology

Validation Methodology: Documenting and Testing Functions Directly

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Calculations represent one of the highest risk components of any computer validation project. When results are displayed on a form or report, users tend to accept those results as correct. Validation has to ensure that the results are actually correct. One common method to validate calculations is to enter a few known values and verify that the expected results are returned. However, even if the results of a calculation are correct in a few cases that does not mean the underlying formula is correct. For that reason, Ofni Systems’ preferred method is to directly verify the function or formula.

The User/Functional Requirements is the appropriate place to document what each formula is supposed to calculate. All of the components of the function should be explained, including any Boolean logic that is used to capture errors or unusual conditions. For example:

  • Force = Mass x Acceleration
  • With valid input, Current = Voltage / Resistance. If Resistance = 0, then Current is NULL.

The Design Specification is the appropriate place to document the actual calculation. It is a good practice for the author of the Design Specification to document the arguments in the calculation to ensure that the calculation does represent the intended calculation; if the author notices that the calculation does not match the requirement, this should be brought to the appropriate person’s attention. For example:

  • Force = Mass x Acceleration. In Excel this is expressed as Cn = (An*Bn), where Column A is Force, Column B is Acceleration and n is row number.
  • Current = IF (Resistance = 0) THEN 0 ELSE (Voltage / Resistance)

The test protocol then ties the User/Functional Requirements to the Design Specification. The protocol procedure describes the requirement. The tester documents the calculation in the results along with the individual components of the calculation. The tester then verifies that the calculation accurately describes the requirement. This does require a tester who is has enough experience to review the formulas, compare them with the requirement and verify that the formula meets the requirement. It also requires that the functions are directly accessible by the tester. The advantage of this method is that the function itself has been directly verified and validated, rather than a few selected inputs.

Getting Started with Validation –
What To Validate, When to Validate, How to Prove You Validated It – 11/15/2012

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Getting started with computer validation can seem like an expensive and impossible task. Too often, organizations only perform validations as a reaction to observations, validating systems one by one. Even if this addresses the immediate observation, the next audit reveals yet another system that is out of compliance creating a history of non-compliance. One of the secrets of computer system compliance is that a well-controlled compliance program adds value to your organization. While validation may seem like a cost, an efficient validation program enhances the value your organization by improving quality to your suppliers, reducing business and regulatory risks, and supporting the training and administration required to allow your organization to grow and thrive.

Attendees will learn the following:

  • Which out your computer systems need to be validated… and which do not.
  • The documentation FDA auditors expect to demonstrate your computer systems have been validated and are operating in a compliant manner.
  • The differences between validation, qualification, user acceptance testing, and internal quality, and when each is appropriate.
  • The regulations that your computer systems must comply with, and the procedures that document that compliance.
  • The procedures required to ensure compliance with 21 CFR 11 and Annex 11.
  • What to ask for when purchasing computer systems that will be used in GxP environments.
  • Industry best practices to maximize your validation resources.
  • How to bring System Owners, Users, and Quality together to improve your business..

On Thursday, November 15, 2012 at 1:00 EDT, join FOI Services and Ofni Systems for a 90-minute teleconference to gain practical knowledge about desktop database compliance and validation, including specific, practical advice on creating compliant desktop databases, validation methodology, and maintaining desktop databases in GxP environments.

About Ofni Systems

Ofni Systems is an industry leader for 21 CFR Part 11 compliance. Their products for Part 11 compliant databases and spreadsheets are used by pharmaceutical, biotech, and medical device companies across the globe, while it’s products for computer validation, auditing, and FDA submissions ensure that their clients meet every requirement for electronic records and electronic signatures. The company provides live desktop support for superior customer support and training and has been providing solutions to their clients since 1999. For more information, call (919) 844-2494 or visit