The Gage Linearity and Bias Study can be used to determine the accuracy of your measurements through the expected measurement range. In other words, it can help you determine if your gage has the same accuracy when measuring objects of different sizes and if your gage is biased when compared to a master value.
1. Choose ProcessMA > Quality Tools > Gage R and R > Gage Linearity and Bias Study.
2. In Measurement, select the column containing the measurement data.
3. In Part, select the column containing the part indicators.
4. In Reference, select the column containing the master measurements.
5. In Process Variation, enter a value for the process standard deviation. You can obtain the value from the Total Variation row of the 5.15*Sigma column of the output from the Gage R&R Study - ANOVA Method.
6. Click OK
Note To select a column of data for a textbox, double-click on any of the column names shown in the list on the left of the dialog box while in the textbox.
Measurement: Numeric.
Part: Text or Numeric; Must contain equal number of data points as the Variable.
Reference: Numeric; Must contain equal number of data points as the Variable.
Process Variation: Numeric.
You want to determine the accuracy of the measurement gage in your plant. You selected five parts to study which represented the range of measurements that you need to take. You also have the master value for each of these five parts. You got an operator to measure the parts in random and 10 times each. You know from a Gage R&R Study that the process variation is 0.8176.
1. Open worksheet ProcessMA > Tools > Data Files > Gage.xls.
2. Choose ProcessMA > Quality Tools > Gage R and R > Gage Linearity and Bias Study.
3. In Measurement, select D – MeasurementLB.
4. In Part, select E – PartLB.
5. In Reference, select F – ReferenceLB.
6. In Process Variation, enter 0.8176.
7. Click OK.
Interpretation
The gage linearity and gage bias account for 1.3% and 5.8% of the overall process variation respectively.