Effective Engineering e-Newsletter – 10/7/2004
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eN-041007:
Quality By Design!
By
Tom Dennis – President, Effective Engineering [tdennis@effectiveeng.com]
In my recent e-Newsletter, eN-040610
– Development Methodology: Test – To Verify, I pointed out the
fact that the purpose of Test is to ensure that the design intent of a
product has been met by verifying that the products conform to their Requirements
(see eN-030925
– Development Methodology: Requirements) and Architecture (see eN-031009
– Development Methodology: Architecture).
The purpose of Test is NOT to attempt to Test or Inspect
quality into a product. Quality
must be designed in! In
another e-Newsletter (see eN-021205
– Poor Quality Products Imply A Poor Quality Company), I point
out the business importance of a company producing high quality products.
This e-Newsletter will expand upon what’s required to achieve a Quality
By Design Methodology.
How is quality most often defined? Three
definitions come to mind:
1) Conformance to requirements.
2) Absence of defects.
3) Fitness for use.
In order to achieve Quality By Design, all three of these
definitions must be part of the methodology.
Let’s start with the first, Conformance to Requirements.
I have stated before the importance of clear, thorough, complete, and
meaningful requirements (see eN-030619
– What Do Your Customers Really Want?, eN-030703
– Product Definition: Define What It Is and What It Isn’t!,
and eN-030717 –
Write It Down and Sign It Off!).
This cannot be stressed enough if you are to achieve Quality
By Design. Everyone
involved must know clearly what the product to be built is and what it
isn’t. The requirements must
reflect the customer experience with the product and must provide sufficient
information for all relevant parties, not just development but also test,
marketing, customer support, and all other relevant organizations, to do their
jobs with certainty. There must be no confusion about this, which means the
requirements must be written, discussed, argued over, agreed to, revised, and
finally signed off on. If the
requirements are not crystal clear to all involved, one party may start
designing with his/her “interpretation” of the requirements, which
may differ from the actual requirements.
Any opportunities for confusion about the requirements will undermine
achieving Quality By Design.
Extra time spent on detailing and defining the requirements is well
worth it. It ensures that
everyone is in agreement, and can actually save time in the overall schedule.
Not to beat a dead horse, but this is really important!
Once the requirements have been signed off, development can begin the next
phase of the development process, which includes converting these requirements
into design specifications of varying levels of detail.
Again, in a Quality By Design Methodology, such design
specifications should be documented and reviewed before coding or schematic
entry or 3D CAD design entry or any other detailed implementation stage
begins. The project needs to be
well planned before the detailed design implementation begins (see eN-031023
– Failing to Plan Means You Are Planning to Fail!).
The development methodology should be followed and enforced, using the
development infrastructure that should be in place (see eN-040902
– Project Management: Planning – Well Begun is Half Done).
Design reviews should be carried out throughout the development
process, and all development tools that help to ensure the quality of the
design implementation should be used at all appropriate stages in the
development process. Interactions
between all of the engineering design disciplines (e.g. hardware, software,
mechanical, quality, performance, usability, etc.) should be frequent and
included in the design review process. Product
Management and Project Management should also be involved at every stage as
deeply as necessary to ensure that everything is on track from their
perspective. The developers
should carry out their own unit testing and module testing before anything is
released to the test group. All
of this will help to achieve an Absence of Defects, before
official testing efforts begin.
The Test organization should be involved in the overall requirements and
development process from the outset, as their contributions can be invaluable,
and participation will help them to properly prepare.
This should include initial product/project discussions, requirements
iterations, planning, and implementation.
They should develop test plans based on the official requirements.
While executing their test plans, they will be able to verify Conformance
to Requirements. Test will also find and report on bugs found, which
will then be fixed (according to criteria established), and then tested again
to ensure the Absence of Defects. In successfully completing their test plans, and releasing
the product to production, test will have verified the products’ Fitness
for Use.
It takes significant effort and discipline to follow all of these steps,
and enforcement of the rules to ensure no short cuts are taken.
Problems will still be encountered and bugs will be found and fixed.
However, if such a methodology is followed, the problems will be fewer,
the bugs less serious, and, more often than not, the total time to complete
development will be shorter. These
are the opportunities to be had with Quality By Design!
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2004
Effective Engineering Consulting Services, All Rights Reserve
