Product Requirements
Design Validation, FDA, Product Requirements and Specifications, QSR
There is often a degree of confusion regarding requirements and specifications, including related topics of verification, validation, traceability and document control. Yet one of the two biggest make-or-break factors in successful product development is requirements/specifications (the second being architecture).
The FDA QSR sometimes uses the terms ‘requirements’ and ‘specifications’ almost interchangeably, such as “Specification means any requirement with which a product, process, service, or other activity must conform”. So in this spirit regarding product requirements and specifications, my take is that products need to meet both their requirements and specifications. So what’s the difference?
As technical, Customer-focused professionals we have two major concerns in this area:
- Meeting Customer needs and expectations
- Designing, Verifying and Validating products to a set of objective, measurable criteria
So I find the following definitions useful:
Requirements are:
- what the product, subsystem, or individual component must do or be to satisfy the higher level Customer needs, or
- a need or expectation that is stated, generally implied, or obligatory
Specifications are:
- a technical translation of the Requirements into measurable terms that can be designed to and verified against, or
- any requirement with that a product, process, service, or other activity must conform
Using these definitions, I suggest the following strategy:
- write the Product Requirements from the Customer or User perspective, in terms that they would use to describe the attributes of the product that meet their needs and expectations.
- write the Product Specifications in clear, unambiguous terms that allow straightforward verification.
- Create a single “Product Requirements and Specifications” document that includes both the Requirements (from the Customer perspective) and Specifications (objective, measurable)
The Requirements and Specifications document (aka ‘Rex and Specs’) can be used by everyone involved in the design and development to 1) keep visibility of the actual User need (Requirements) and 2) have objective, measurable criteria (Specifications) to meet. Here’s a picture of Rex and Specs to help you remember him.
I’ll cover this in more detail in future ‘tips’, but the next step is to Validate the Requirements and Specifications document itself, with actual Customers and/or Users:
“Design Validation means establishing by objective evidence that device specifications conform with user needs and intended use(s).”
Examples of Requirements and Specifications (aka ‘Rex and Specs’):
Requirement: the product shall be lightweight.
Specification: the product shall weigh less than (5) lbs.
Requirement: the product shall be easy to use.
Specification: the product shall be able to be set up and started operation by a Registered Nurse in less than (1) minute on average.
Requirement: the product shall run a long time on battery.
Specification: the product shall be able to run with all functions operating for a minimum of (8) hours from a fully charged battery.
Requirement: the product display shall be easy to read.
Specification:
- The product LCD shall be viewable from a distance of (2) meters over an angle of +/- 45 degrees horizontal and +/- 15 degrees vertical.
- All product display screens shall be readable by a person with 20:20 vision from a distance of (1) meter over an angle of +/- 45 degrees horizontal and +/- 15 degrees vertical.
Requirement: the product Heart Rate readings shall be accurate.
Specification:
- The product shall measure the ECG Heart Rate from 30 to 250 bpm.
- The product shall measure the ECG Heart Rate with an accuracy of ±2% bpm.
Requirement: the implant shall be biocompatible
Specification: the implant shall be made from implant grade 315 Stainless Steel.
Requirement: the software application shall run under a readily available Operating System.
Specification: the software application shall run under Microsoft Windows® XP Operating System.