Lean Six Sigma For Dummies. Brenig-Jones Martin
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also be able to prompt new opportunities (see Chapter 8 for more on getting the right balance of measures).
The following sections provide a little more detail about the five DMAIC phases. Figure 2-1 shows how the phases link together, though the process is not necessarily linear. It could be that in the Define phase, for example, the problem that you are planning to tackle can’t be adequately quantified. In the Measure phase, you’ll be collecting data that enables you to go back to Define and update your description of the problem.
© John Morgan and Martin Brenig-Jones
Figure 2-1: The five phases of DMAIC.
When you start an improvement project, ensuring that you and your team understand why you’re undertaking the project and what you want to achieve is an essential ingredient for success. With a DMAIC project, you start with a problem that needs to be solved. Before you can solve the problem, you need to define it – not always as straightforward a process as you may think. One of the key outputs from the Define phase is a completed improvement charter.
The improvement charter is an agreed document defining the purpose and goals for an improvement team. It can help address some of the elements that typically go wrong in projects by providing a helpful framework to gain commitment and understanding from the team. Keep your charter simple and try to contain the document to one or two sides of A4 in line with the example shown in Figure 2-2.
© John Morgan and Martin Brenig-Jones
Figure 2-2: A sample improvement charter.
The improvement charter contains the following key elements:
✔ A high-level business case providing an explanation of why undertaking the project is important.
✔ A problem statement defining the issue to be resolved.
✔ A goal statement describing the objective of the project.
✔ The project scope defining the parameters and identifying any constraints.
✔ The CTQs specifying the problem from the customer’s perspective. Unless you already have the CTQs, these may not be known until the Measure phase.
✔ Roles identifying the people involved in and around the project, expectations of them and their responsibilities. The improvement charter forms a contract between the members of the improvement team, and the champion or sponsor.
✔ Milestones summarising the key steps and provisional dates for achieving the goal.
The improvement charter needs to be seen as a ‘living document’ and be updated throughout the various DMAIC phases, especially as your understanding of the problem you’re tackling becomes clearer.
© John Morgan and Martin Brenig-Jones
Figure 2-3: Creating an affinity diagram.
© John Morgan and Martin Brenig-Jones
Figure 2-4: A sample interrelationship diagram.
It’s highly likely that affinity and interrelationship diagrams will be used at the beginning of a design project, where the DMADV method would be used rather than DMAIC.
Figure 2-3 shows the steps in the creation of an affinity diagram. The process works best if you use sticky notes and silently brainstorm ideas on an agreed issue statement; for example, ‘what issues are involved in introducing Lean Six Sigma into our organisation?’
Follow these rules:
✔ Use one idea per sticky note.
✔ Write statements rather than questions.
✔ Write clearly.
✔ Don’t write in upper case (reading lower-case words is easier).
✔ Avoid one-word statements (your colleagues won’t know what you mean).
✔ Include a noun and verb in each statement.
✔ Don’t write an essay.
After everyone has finished writing their sticky notes, maintain the silence and place them on the wall, as shown in the first part of Figure 2-3. Move the notes into appropriate themes or clusters (see the middle figure), you’ll probably need to break the silence here. Finally, give each theme or cluster a title describing its content (see the final figure). Ensure that each title provides enough description; doing so is helpful for when you move into the interrelationship diagram, shown in Figure 2-4.
An interrelationship diagram identifies the key causal factors or drivers for your programme or project, by enabling you to understand the relationships between the themes or clusters. In looking at the different pairs of clusters you’re trying to see if a cause and effect type of relationship exists, so does ‘this’ have to be done before ‘that’, or does ‘this’ drive ‘that’.
In Figure 2-4, the headers for the themes or clusters from the affinity diagram have been put into a clock face on a flip chart and you now work your way round looking at the relationship between each pair. As you do so, you need to consider whether a relationship exists or not, and, where it does, determine which has a greater effect on the other – for example, ‘must this happen before this does?’
If a relationship does exist between two clusters, connect them with a line. Importantly, either there is a relationship or there isn’t, so don’t use dotted lines – you might start with a pencil, though! Agreeing some ground rules is sensible to ensure the relationships are tangible.
After you’ve determined the ‘causal’ cluster, draw an arrow into the ‘effect’ cluster. Some discussion is likely to take place about which way the arrow faces, but it has to go one way or the other – two-headed arrows are not allowed! In Figure 2-4, you can see that A drives B, but that B is the driver of C. The numbers represent arrows out over arrows in.
The finished diagram can be presented as shown in Figure 2-5, and you can