About this lesson
Gage R&R Methodology
There is a recommended process for conducting a Gage R&R study. This methodology guides the study manager through the steps to a successful conclusion.
When to use
Whenever planning a Gage R&R study, use the planning and executing methodologies.
A Gage R&R Study is a process just like most other business activities. As such, there is a best practice methodology that should be followed to maximize the effectiveness and minimize the cost and business disruption to the business. The process can be divided into three phases:
- Planning – this involves focusing the study, designing the study and then coordinating for all the resources needed to conduct the study.
- Data collection – this is the phase in which data items are measured and data is recorded for analysis.
- Analysis – this phase determines the level of repeatability and reproducibility. This phase is quite different depending upon whether the data is variable data or attribute data.
For our purposes, we have divided this methodology into two parts – planning and executing.
- Identify the measurement that is to be investigated – this limits and focuses the study.
- Identify the measurement approach used for this measurement – this further limits and focuses the study. If no system is currently in use, one needs to be developed so the Gage R&R becomes part of the validation of that new system.
- Design the study (# appraisers, # items, # replicate trials, location and environment).
- Communicate the plan – inform stakeholders of upcoming activities and their participation requirements.
- Coordinate the resources – availability of appraisers, creation of the sample items to be measured, access to the measurement equipment, other needed support.
- Train appraisers if required.
The results of the study design and planning are often captured in the data collection form. These forms are very different depending upon whether the measurement is comprised of variable data or attribute data. If using a statistical software application such as Minitab, it will design the study and create the data collection form. If doing the analysis manually, the form is normally created in a spreadsheet application such as Microsoft Excel. A unique feature about the attribute data collection is that you can choose to include a reference standard for each item and that allows additional calculations for Miss Rate, False Alarm Rate, and Effectiveness.
Variable data – 3 appraisers, 10 items, 3 replicate trials
Attribute data – 3 appraisers, 30 items, 2 replicate trials.
Hints & tips
- It is very easy to confuse the items once they have been randomized for measurement. Be sure to keep track of which is which and record data correctly.
- Using an application like Minitab makes this process go very quickly and smoothly.
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