Statistical Measurement Process Control (SMPC) Analysis 
SMPC analysis is a new and powerful way to refine our estimates of the biases and in-tolerance probabilities for the measuring parameter and subject parameter.  In measurement situations where we have a priori knowledge of measuring parameter and subject parameter statistics, the roles of measuring parameter and subject parameter are reversible.  This means that, with SMPC, we can use information from a measurement result to estimate the values or biases of both the subject parameter and the measuring parameter. Using SMPC, we can also estimate the uncertainties in these values or biases.

Briefly stated, SMPC determines a posteriori (post-measurement) values from a priori values (i.e., values indicated prior to taking measurements) combined with measurement results. In most cases, the a priori knowledge of the subject parameter and measuring parameter includes the tolerance limits and associated in-tolerance probability for each parameter. 

The results of SMPC analysis are shown on the SMPC Analysis Screen, activated by selecting SMPC Analysis from the SPC menu on the Main Screen. Features, options and data boxes for the SMPC Analysis Screen are described below.

Pre-Analysis Data
The upper and lower tolerance limits and associated in-tolerance probabilities displayed in the Pre-Analysis Data section are the parameter specifications initially established using the Subject Parameter Bias Uncertainty Worksheet and the Measuring Parameter Bias Uncertainty Worksheet. These are the specifications that we use to estimate parameter bias uncertainties prior to analyzing the measurement results.

Uncertainty Analysis Results
Information about the uncertainties in the error sources is displayed in this section. This includes the uncertainties in the subject parameter and measuring parameter biases, measurement sample statistics, and other process uncertainties. 
This uncertainty analysis information is used in combination with the pre-analysis data to refine the estimates of the biases and in-tolerance probabilities for the measuring parameter and subject parameter. 

SMPC Analysis Results
The refined estimates for the subject parameter and measuring parameter biases are displayed in this section. Selecting the Measured Values or Deviations option at the bottom of the screen, and the display units from the drop-down list, will affect the values displayed.

 
When the Measured Values option is selected, a refined estimate of the subject parameter mean value is displayed in the Estimated Parameter Value box. Checking the adjacent checkbox selects the SMPC Sample Source and places this value in the Estimated True Value box on the Main Screen. 

The SMPC Analysis Results table displays the pre-analysis mean values and tolerance limits for the measuring parameter and subject parameter in nominal units. The revised in-tolerance probabilities and estimated biases and confidence limits for the measuring and subject parameter are also displayed. You can enter the desired Confidence Level and click the Re-calc Confidence Limits button to re-compute the Confidence Limits.

When the Deviations option is selected, the difference between the estimated true value and the nominal value for the subject parameter is displayed in the Deviation from Nominal box. Checking the adjacent checkbox selects the SMPC Sample Source and places this value in the Estimated True Value box on the Main Screen. 

The SMPC Analysis Results table displays the pre-analysis mean deviations and tolerance limits for the measuring parameter and subject parameter in deviation units. The revised in-tolerance probabilities and estimated biases and confidence limits for the measuring and subject parameter are also displayed. You can enter the desired Confidence Level and click the Re-calc Confidence Limits button to re-compute the Confidence Limits.