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Data Is A Key Component of Six Sigma
Data Is A Key Component Of Six Sigma Implementation
By Joe Barckett
One of the key components of Six Sigma is that the improvement process is data driven. As our Black belts and Green belts move through the DMAIC process, we do not expect them to be empty-headed; rather we encourage them to utilize the experiences and intuition of both themselves and their team. In addition, we require them to back up their decisions with data.
Once this process is understood, the question of "What data?" arises.
The SIPOC (Suppliers, Inputs, Process, Outputs, Customers) map can be one of the tools used to help identify some of the necessary data. This high level map will help us by listing the inputs and outputs of the process. The "As Is" process map is another source of information.
From these two maps we can begin to list the three types of indicators we will use in our process improvement project: input indicators, process indicators, and output indicators.
Output indicators (Y's) are those key metrics that measure the accuracy in meeting the Critical Customer Requirements (CCRs). Generally, they are measured after the product or service is complete. These indicators are not helpful in predicting, thus making them reactive rather than proactive. Output indicators are necessary because they help us to understand process performance from the customer's perspective. The key output indicators should be identified in or before the Define phase. If pizza delivery is the process the team is trying to improve, then an output indicator might be a pizza temperature of 130º F +/- 10º F at the customer's house.
Once the output indicators are determined, we take a step back into the process under study, and consider process indicators (x's). Preferably, the selected process parameters will have a direct affect on the output indicators (Y's). These are considered ideal process indicators and may be predictive. The team should ensure they have identified at least one process indicator for each CCR. These process indicators will be used in the Analyze phase to help validate root causes. For our pizza delivery process, key process parameters that affect pizza temperature may be oven temperature, packing cycle time or delivery person.
The last set of indicators that will be discussed in this article are input indicators. From the SIPOC map, we identify the process inputs and can list potential input indicators. These may be less predictive than the process indicators but are just as important. Because they are inputs, they generally relate to the suppliers' performance. Oven gas flow or electrical voltage may be key input indicators for our pizza delivery process.
Once the output, process, and input indicators have been determined, the list can be examined for balance. It is important to confirm that the list is balanced from a financial, quality, productivity and timeliness viewpoint. You do not want a set of metrics that sacrifice quality for productivity, or timeliness for cost.
Once the indicators have been identified, we can proceed to the next Measure steps: writing Operational Definitions and performing Measurement System Analysis (MSA).
In summary, there are three types of indicators that help in the search for validated root causes. It is important to gather data at all levels of the SIPOC, and assure that the team has a balanced set to work with in their improvement system.
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