Measure
Measurement System Analysis – Continuous Data
In Article 19, we explored the Measurement System Analysis for Attribute Data. Now, let's delve into Measurement System Analysis for Continuous Data in the Measure Phase in this article.
In Measurement System Analysis for Continuous Data, it's crucial to ascertain the precision of the system, instrument, device, or gauge. To achieve this, we repeatedly measure the same item under consistent conditions, with the same operator, device, and item location. Each measurement involves fully mounting and dismounting the item, while also subjecting the gage to a full range of normal use.
A sample size of 25 or more measurements is generally considered adequate to capture the variability in the measurement process. However, it's important to note that the more samples taken, the better the understanding of the measurement system's behavior.
For this test we calculate the mean – x̄, and the standard deviation – s
Device precision should ideally be less than 1/10 of the tolerance (s < 1/10 x tolerance). If the standard deviation (s) exceeds 1/10 x tolerance, the measurement system is deemed unacceptable due to a lack of precision. In such instances, it's imperative to identify and rectify sources of error, which may involve replacing the device
Device accuracy can be estimated by comparing the measured values to the true value of the test unit. The inaccuracy, or bias, can be calculated as ( Inaccuracy (Bias) = Measured Value - True Value)
Precision Vs. Accuracy - Target Analogy
As the final point, the observed variation of a product or process comprises:
· The inherent variation of the product/process itself.
· The variation introduced by the measurement system.
This article concludes the Measure Phase. Below is an illustration of everything covered in this phase. I encourage you to continue our journey with us. Join us in the next several articles to cover the Analysis phase of Six Sigma.
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