topic Re: Variability Gauge Bias Report Error in Discussions

Variability Gauge Bias Report Error

ERoderz — Fri, 09 Jun 2023 00:59:50 GMT

When attempting to run the Bias Report in the MSA module, I receive this error. I'm not quite sure what it means or how to rectify it. Please help.

Re: Variability Gauge Bias Report Error

Mark_Bailey — Thu, 30 Mar 2023 18:11:20 GMT

I think you have a data problem. One column should identify the part. Another column should provide the associated standard value. It appears that some standard values for the same part contradict other values.

I suggest launching the Distribution platform with the part ID and standard value columns. Select each part in turn in the histogram (click on the bar) and see if there are instances with more than one standard value.

You could also temporarily change the modeling type of standard value to nominal. Then select Tables > Summary, enter both part ID and standard value as a group and click OK. The table you get should also help identify the problem.

Re: Variability Gauge Bias Report Error

FlowData321 — Thu, 30 Mar 2023 20:23:29 GMT

Hello Mark,

We've examined the data and now understand why the report is having an issue. We have a predicate instrument (standard) and a test instrument (Y, response). The Donor is the "Part, Sample ID". However, we ran a control sample over multiple days. Therefore, we have 6 replicates of the control donor number. If the control donor number is excluded with a data filter, the bias report is able to run. However, if the bias report cannot handle repeated measure, perhaps the EMP Measurement Systems Analysis is the wrong test. What is the correct test to determine whether our test instrument is biased?

Re: Variability Gauge Bias Report Error

Mark_Bailey — Fri, 31 Mar 2023 17:04:14 GMT

I created an example for this MSA. I hope it illustrates the data, data layout, and analysis launch that should work. First of all, your data should have a layout similar to this example:

The MSA should be launched like this:

After selecting the Linearity and Bias Test from the platform menu, you should not see that error message. You should see a report like this:

Here is the script I used to create this example:

Names Default to Here( 1 );

dt = New Table( "Bias Analysis",
	New Column( "Donor", Numeric, Nominal, Values( Shape( Transpose( Repeat( 1::10, 2 ) ), 20, 1 ) |/ Repeat( 0, 6 ) ) ),
	New Column( "Predicate", Numeric, Continuous, Values( Shape( Transpose( Repeat( J( 1, 10, Random Normal( 15, 2 ) ), 2 ) ), 20, 1 ) |/ Repeat( 15, 6 ) ) ),
	New Column( "Test", Numeric, Continuous, Values( (:Predicate << Get As Matrix) + J( 26, 1, Random Normal( 0, 0.1 ) ) ) )
);

dt << New Script( "MSA by EMP",
	EMP Measurement Systems Analysis(
		Y( :Test ),
		X,
		Part( :Donor ),
		Standard( :Predicate ),
		Model( Crossed ),
		Dispersion Chart Type( Range ),
		Max Iter( 100 ),
		Conv Limit( 0.00000001 ),
		EMP MSA Analysis( :Test, Linearity and Bias Results( 1 ) )
	)
);