Causes of Measurement Variation
April 3, 2025
The purpose of measurement system is to validate the measurements before they are considered as factual data and used as a basis for decision making. Any experienced Six Sigma executive knows the reality that the measurement system is nowhere nearly as good as you think it is. People who conduct the measurement system analysis for…
Converting Data to Information: The goal of a six sigma project is not to produce an overwhelming amount of data that ends up intimidating the concerned people. The goal is to find out as much data as possible and convert it into meaningful information that can be used by the concerned personnel to make meaningful…
Measurement Systems Analysis is a complicated exercise. However, Six Sigma provides a step by step procedure to conduct it. Also, as usual, the focus of the executives should be to understand the focus of the exercise and interpretation of the results. The complex calculations can be performed by software. Here is the 4 step procedure.…
Process maps can be built in the usual way wherein sequence is the primary concern or in the swim lane pattern. In the swim lane pattern along with sequence, accountability is also formally recorded. This is because each group of participants is recorded separately and the time taken by them to perform a task is also recorded. It is for this reason that swim lanes are useful when handoffs between participant groups are a major concern.
Once you have decided on the type of detailed process map, begin by identifying the starting point and the ending point of the sub process. After this map the sequence of actions and decisions that are involved. It is unusual for someone to miss the key actions in a sub process. This is because they are very visible to the naked eye. However the decisions involved are likely to be missed. Hence consider whether all decisions as well as all alternative paths have been included in the diagram.
The next step is to write down exactly what the process creates i.e. the outputs. Outputs are usually tangible items like the product that is being manufactured or a document that has been created. In case of service environments, the delivery of the service as planned is the final output. Listing down these outputs also make it clear to the person mapping the process whether they are as per the Critical to Quality metrics that have been listed down by the customers.
Based on the outputs listed, make a list of the input variables that will are and should be required for the working of the process. A detailed process map creates a scenario whereby the analyst has to map the variables and the decisions step by step, making it difficult to miss them.
The typical end result of the above step is a long list of input variables. However, lists do not work very well for management. They have to be stripped down to categories which are relatively much easier to manage. Therefore, the input variables are classified in a myriad of ways. On the basis of their type they are classified as the 6 M’s, 8 S’s etc like in the Fishbone Diagram. On the basis of whether the variables can be controlled they are classified as controllable and uncontrollable. The uncontrollable ones are regarded as risks.
Once the output and input variables have been listed, data must be recorded by either simulating the process or actually running it. Then correlations must be done between the state of inputs and the desirable outputs to find out the critical inputs.
Check whether the ideal state of inputs is in fact ideal. Run a simulation with the prescribed state of variables. Check whether any undesirable consequences do emerge.
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