# How to define Calibration Acceptance Criteria

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#### xixide

I have some questions need you help.
1. How to define the calibration acceptance criteria, as calibration report only show the standard value vs measurement value, no conclusion.I know need user define, but based on what.
2. What the meaning of the uncertainty, how to use it.
Below is the part of the calibration report of OGP.

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Good morning!

A question... can you please interpret the titles of the different columns? That might be helpful.

Do you have any specifications from the manufacture for these instruments?

Do you have any process tolerances of how accurate the device is to be for its use?

#### dgriffith

##### Quite Involved in Discussions
I have some questions need you help.
1. How to define the calibration acceptance criteria, as calibration report only show the standard value vs measurement value, no conclusion. I know need user define, but based on what.
The acceptance criteria is usually an engineering decision. If not an established tolerance (maximum permissible error) from a manufacturer, then it could be a value established by you based on its intended use. What is it used for, and how much error/deviation from the target value can you tolerate? It could also be a calculated deviation from the tolerance based on risk, sometimes called a guard band. Just know that no measurement is exact or is without error (as far as we lowly techs and engineers are concerned).
Also, if it is a high level standard, there may be no tolerance, but only an established value with an uncertainty. You would use this value with its uncertainty when calibrating a lower level standard.
2. What the meaning of the uncertainty, how to use it.
Below is the part of the calibration report of OGP.
The world will revolve many times before that question gets fully answered . . .but, the short of it is a range of values within which the true value lies, with some stated level of confidence. The k=2 in the last column indicates a confidence of approximately 95% that the listed errors in the middle columns are correct, plus or minus the last column, assuming symmetry.

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X

#### xixide

I have some questions need you help.
1. How to define the calibration acceptance criteria, as calibration report only show the standard value vs measurement value, no conclusion.I know need user define, but based on what.
2. What the meaning of the uncertainty, how to use it.
Below is the part of the calibration report of OGP.
1. First column: Reference value unit mm for different axis
2. Second column: actual measurement error for 1, 2,3 times measurement
3. Last column:uncertainity