Just as the DMAIC steps have guided thousands of Lean Six Sigma (LSS) teams to conduct their corrective projects, this article (part 1 of 2) will define a repeatable set of six steps to prevent problems, using familiar LSS tools, or simple adaptations of them. There is an excellent set of re-usable LSS tools, methods and best practices (TMBP) to work with as we approach our preventive FutureSigma strategy in our process or project work.
Throughout these steps, we will reference the Potential Problem Prevention and Impact Mitigation Analysis (P3IMA) table. The P3IMA table is an adaptation of the Failure Modes & Effects Analysis tool (FMEA) and is the heart of the problem prevention process. The contents of P3IMA table are developed during these 6 steps, culminating in the preventive and contingent action definition and selection for the process for which problems are being prevented.
In the same fashion as one can perform a corrective DMAIC (Define-Measure-Analyze-Improve-Control) project, one can perform a preventive project as follows:
Step 1-Plan and Rank Tasks of the Preventive Project
What to do in Step 1:
a) Design a plan of detailed tasks in their serial and parallel flows-what you are going to do!
b) Perform value-stream analysis and confirm the process' inherent robustness
c) Rank and prioritize the value of each task relative to one another
This step sets the stage for opportunities to apply preventive and contingent action for the process that is the subject of the preventive project. Of course, we also have the option to prescribe neither preventive nor contingent actions. In this case, if a problem does surface, the use of corrective action will be the only alternative left to set things right.
It is important to lay out the process' tasks in an appropriate process map, flow diagram or other format that displays the flow of activity in enough detail that you can discern and define potential problems in Step 2. The tasks should undergo value stream analysis; we want to do our remaining steps on a high-value set of tasks. There will be potential problems enough for us to deal with, so we don't need to assess tasks that are not worth doing. If each task can be justified and the relationships between the tasks do not show signs of significant conflict then we have a good starting point from which to proceed. We refer to such a flow of value-adding tasks basically or inherently robust - they are in reasonable harmony in this unstressed format. Such task flows should be fundamentally resistant to mild sources of variation. Finally, rank and prioritize the relative importance of each task. This will help when we quantify the impact if a problem is allowed to run its course in any one of the tasks. We must be ready to focus on the most important tasks first.
Re-use these LSS TMBP's for Step 1
- Project plans and RACI chart
- Process Maps: SIPOC, etc.
- Flow and Swim-lane diagrams
- Value stream analysis
- PERT and Gantt charts
- Pareto Charts
Step 2-Define Potential Problems
What to do in Step 2:
a) Define potential problems that can occur within and between the tasks
b) Document the mistakes or errors that characterize each problem
c) Identify leading indicators that measure the onset of each problem
Each task is assessed for potential problems that can occur within it and also between it and other interrelated tasks. Ask what can go wrong with the task. The potential problems include the errors, mistakes and outright failures likely to occur if nothing is done to prevent or mitigate them. Be sure to explore the question of what could happen if a task is rushed or short-changed in any way. Here we can benefit from cause and effect analysis, fault trees, fishbone diagrams and brainstorming to fill out an affinity diagram or KJ analysis around categories or groups of different things that can go wrong.
Re-use these LSS TMBP's for Step 2:
- P3IMA table (an adaptation of the FMEA tool)
- Fault tree
- KJ or affinity diagram
- Cause & effect matrix
- Fishbone diagram
Step 3- Document and Evaluate the Root Causes
What to do in Step 3:
a) Document and evaluate the root causes of the potential problems
b) Understand the mechanisms behind all impending or latent problems
Step 3 is where we apply the preventive form of root cause analysis. What are the fundamental causes that initiate and then escalate the problem into its complete and most disruptive form? The noise diagram helps lay out the underlying causes that breathe life into a growing and maturing problem. This requires taking a building block or mechanistic view of what must come together to really give a potential problem its structure and enabling dynamics.
Re-use these LSS TMBP's for Step 3:
- Preventive root cause analysis (an adaptation of the Root cause analysis tool)
- P3IMA table (an adaptation of the FMEA tool)
- Fault tree
- Cause & effect matrix
- Fishbone diagram
- Y=f(X) flow down
- Traceability flow down
- 5 Whys analysis
- P-Diagram and Noise diagram
- Input-Output-Constraint diagram
Next month we will conclude with the remaining 3 steps of the six-step problem prevention process.
