Tuesday, June 22, 2004

FDD Six Sigma #2:DMADV

A few more thoughts on FDD and Six Sigma process…

DMADV

The Design for Six Sigma (DFSS) process is known as DMADV - Define, Measure, Analyze, Design, Verify. This process is generally used for product design before manufacturing. The DMAIC process is then used to refine the manufacturing process through reduction of common cause variation. The DMADV process is designed to remove variation between what the customer wants and what actually got designed. It’s a different kind of variation perhaps but it is still variation. We get variation from uncertainty and change. There is potential conflict between DMADV and the agile movement. DMADV seems to take the traditional approach of eliminate variation by “getting it right first time” rather than “responding to change”. However, we could take a more liberal view of DMADV and say that we are still DMADV compliant if we can accept change late in our design. We need to be able to accept change late in order that our design matches what the customer wanted. Hence, you cannot achieve good DMADV results without accepting change in the agile fashion.

DMADV in Brief

1. Define: Initiate, scope and plan the project.
2. Measure: Understand customer needs and specify client-valued functionality
3. Analyze: Develop design concepts and high level design
4. Design: Develop detailed design and control/test plan
5. Verify: Test design and validate it meets customer requirements

<!—StartFragment—>DMADV with FDD and Agile Management

Now it ought to be somewhat obvious that FDD includes many of the features required for a DMADV complaint process with its analysis and modeling, design and verification steps. But it is also clear that FDD puts a twist on it. DMA becomes more like AMD - Analyze, Measure and Define. Perhaps DMADV truly needs to become AMDDV in order to embrace the uncertainty in design problems and to acknowledge the variability inherent in design problems.

Define:
In FDD we define the overall scope as a set of Subject Areas in which we’d like to develop a system. However, the scope is not agreed until after process 1 - Modeling - and process 2 - Build a Feature List - are completed. Both of these processes are defined using an ETVX (Entry, Task, Verification and Exit) template. Hence, there is quality assurance built in to the method which is compliant with the spirit of Six Sigma and DMADV. After process 3 - Plan by Feature - there is an agreed scope and plan for the project. Hence, FDD achieves a DMADV compliant Define step as an exit criteria from process 3 - Plan By Feature.

Measure:
In FDD we measure Features as the basic unit on design in process (DIP) inventory and the basic unit of client-valued function. A Feature List - a definitive list of what will be measured in the project - is an exit criteria from process 2 - Build a Feature List. Process 2 has an ETVX template and has quality assurance in the spirit of Six Sigma designed into the method.

Analyze:
FDD process 1 - Develop an Overall Model - is the analysis step which enables the precise definition of the scope and the identification of Features for tracking and measuring the project. The domain model provides a high level design and equivalent interaction architecture modeling for the UI completes the design concepts. The exit criteria for process 1 provide Analyze step for Six Sigma.

Design:
Process 4 and 5 in FDD - Design by Feature and Build by Feature - represent the Design step for DMADV. Again both process have ETVX templates and quality assurance is built in to the process.

Verify:
All 5 FDD processes have verification steps in their ETVX templates. Inspections and cross-functional review are present at each stage in the process. Ultimately quality control testing is applied to validate that the agreed scope was delivered in the working software.

My overall feeling is that FDD is very compatible with DMADV though it can’t be mapped to it precisely. I feel that FDD’s 5 processes are more attuned to the agile goals of responding to change and delivering frequent, tangible, valuable working software. DMADV seems like a traditional “big requirements up front” process which denies the underlying variability and uncertainty in design problems. AMDDV - Analyze, Measure, Define, Design and Verify - might be a better Design for Six Sigma (DFSS) process because it better reflects the roots of Six Sigma in the fundamental understanding or variation.