Although the philosophy behind
QFD is solid – that is to use customer inputs to create products
that customers want – the house of quality, which is the
multifaceted matrix used pervasively as the tool for
implementing QFD is the wrong tool for the job of innovation.
Innovation is the process of finding solutions that address
unmet customer needs. The house of quality emerged as a tool to
ensure the product was designed as conceptualized as it went
through the product development process – not to enable the
innovation process. Using the house of quality for innovation
has forced QFD practitioners to execute workarounds and employ
questionable practices that introduce variability into the
innovation process.
For example, QFD practitioners limit the number of customer
inputs they place into the house of quality to a workable
number, usually setting the limit at about 30 inputs. This means
that when 100 inputs exist, some two-thirds of the potential
customer inputs are ignored, no doubt some of them critical.
Furthermore, the actions taken to limit the number of inputs, by
either excluding them or combining them, make the process
inherently unstable. Who decides which of the inputs to exclude
or combine, and how? If a company does decide to include all 100
inputs in the matrix, it would take a team of people 167 hours –
or nearly 21 8-hour days to complete the relationship analysis
assuming one minute of analysis per relationship. Ironically,
this exercise is not even needed when desired outcomes are used
as the inputs into the innovation process, because pure,
solution-independent inputs have no relationships.
As another example, the inputs used to make decisions in the
house of quality are twice removed from the customer’s actual
inputs – once when the company defines engineering metrics and
again when it prioritizes them through relationship analysis.
Rightfully so, most companies prefer to base decisions on direct
customer inputs as prioritized by the customer. Why introduce
unneeded variability?
Lastly, and probably most incriminating, the house of quality
can be gamed. By knowing how to work the relationship analysis
or by using marketing factors as they are called or other
factors to adjust the prioritization of the metrics, a clever
employee can ensure certain customer inputs get a top priority.
All these structural limitations introduce a source of
variability and uncertainty to the process.
Our view is that the outcome-driven innovation methodology is a
far superior method for identifying solutions that address unmet
customer needs and to deliver on the philosophy behind QFD. And
the house of quality – if it has a place in the development
process – should be to help with the quality deployment of the
solution through the development process to ensure the product
is designed and manufactured as conceptualized.
