Linearity and Bias Study Compliance Requirements

[Calibrator24]

Hi everyone, here in our company, Linearity and Bias studies are being conducted by calibration personnel using calibration reference standards available. I’d like to know if this is enough to comply with the MSA Standard or does the Standard specifically required that Linearity and Bias shall be performed by the gauge users using working standard?

Will it matter if a Calibration technician or a Gauge user is doing the study?

 

[Calibrator24]

on the MSA manual pp73 Section C- Preparationfor a Measurement System Study, item #3 it states there:

" 3) Since the purpose is to evaluate the total measurement system,the appraisers chosen should be selected from those who normally operate the instrument."

Is this statement, or are all the statements on Sec.C Preparation... applicable for Linearity & Bias?
Please enlighten.

 

[ajay.khosla]

whether you are dong linearity study or bias study or stability study(Location errors or you are doing repeatability and reproducibility study(width erreors).
Its always good that you choose the persons who normally do inspections
If your calibration is done perfectly,bias need not to be done.

 

[Calibrator24]

whether you are dong linearity study or bias study or stability study(Location errors or you are doing repeatability and reproducibility study(width erreors).
Its always good that you choose the persons who normally do inspections
If your calibration is done perfectly,bias need not to be done.

I agree with you that Gauge R&R should be done by the persons directly involved in the process, but for Bias and Linearity, I dont get it. In Linearity and Bias study, the equipment variation is supposed to be the focal point and not the operator, right? I f this is the case, then why don't we use the best standard available and the best person to perform the study, to minize the error and measurement system uncertainties?

 

[falconer65]

Cal,

In the end, it is between you and your customer.

The AIAG MSA reference manual is a good place to start. It was intimidating to me, but I waded in and am still learning to swim. And it is only a reference. I have had to pull from many sources, like the Cove here.

Bias is the difference between the true value and the observed average of measurements on the same part. It seems bias is meant to take into account the total variance of the measuring system. So yes, the end users should be involved.

Linearity is the difference in bias over the expected operating range. So, yes again, the end users should be involved.

Now here is where it gets tricky. You asked if "shall" was mentioned by the Standard or the MSA reference manual. 7.6.1 only says measurement systems analysis "shall" be done, not specifically how. The MSA says in the forward that it only has guidelines, the MSA is only a reference manual. The Standard and the AIAG manuals have to cover a wide spectrum of businesses and processes, so they are not specific to any one business or process.

 

[Jomar Ramos]

Anyone who has an excel sheet for Gage Bias ang Linearity Study?

 

[harry]

Anyone who has an excel sheet for Gage Bias ang Linearity Study?

Welcome to the Cove.

Such files are normally found in the Post Attachments List

You can search with keywords such as: bias

 

[Jomar Ramos]

Thanks Harry

 

[eturkan]

Do we use gage blocks or parts for Linearity study ? AIAG MSA Pg96 says "parts" and also requires randomization.

 

[Jomar Ramos]

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