Measurement Systems Analysis

Gage R&R studies are the best practice for determining measurement system process capability and maintaining that capability. They quantify the level of precision that the measurement system will deliver. Key principles for conducting effective Gage R&R studies are introduced in this lesson including those for managing the appraisers and for selecting the items for measurement.

When designing the study, there are several critical considerations based upon the type of test (destructive or non-destructive), the discrimination of the test system, and whether attribute tests can designate an item into multiple categories beyond Pass/Fail. These considerations impact the accuracy and performance of the analysis.

This lesson reviews best practices for executing the Gage R&R Study plan. It also explains how the results are presented for both variable data Gage R&R studies and attribute data Gage R&R studies. This includes presenting the target values of acceptable measurement system performance.

Variable data Gage R&R Studies calculate a comprehensive measurement that can be used to determine the efficacy of the measurement system that is creating variable measurements of product or process characteristics. This lesson describes those calculations and highlights where weaknesses in the system will be exposed.

This lesson walks through an example of a variable data Gage R&R analysis. The example is demonstrated using manual data collection and equations with a spreadsheet in Microsoft Excel. The same example is then demonstrated using the statistical software program Minitab, which is often used to conduct analyses for Lean Six Sigma projects.

Attribute data Gage R&R Studies generate a number of metrics that are used for judging the performance of the measurement system used to evaluate pass/fail attribute data. In this lesson, each of these metrics is described and the method of calculation is explained.

This lesson walks through an example of an attribute data Gage R&R analysis. The example is demonstrated using manual data collection and equations with the Microsoft Excel spreadsheet application. The same example is then demonstrated using the statistical software program Minitab, which is often used for analyses with Lean Six Sigma projects.

Gage R&R studies can be done with automated test equipment to be certain that they are providing accurate and precise results. These are known as Type 1 Gage studies. These studies can be used with any type of automated checking or testing system, not just manufacturing systems. A satisfactory Type 1 Study is often needed to convince stakeholders to have confidence in automation.