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2. Measurement Process Characterization
2.6. Case studies
2.6.3. Evaluation of type A uncertainty

Run the type A uncertainty analysis using Dataplot

View of Dataplot macros for this case study This page allows you to repeat the analysis outlined in the case study description on the previous page using Dataplot . It is required that you have already downloaded and installed Dataplot and configured your browser. to run Dataplot. Output from each analysis step below will be displayed in one or more of the Dataplot windows. The four main windows are the Output Window, the Graphics window, the Command History window, and the data sheet window. Across the top of the main windows there are menus for executing Dataplot commands. Across the bottom is a command entry window where commands can be typed in.
Data Analysis Steps
Results and Conclusions
Click on the links below to start Dataplot and run this case study yourself. Each step may use results from previous steps, so please be patient. Wait until the software verifies that the current step is complete before clicking on the next step. The links in this column will connect you with more detailed information about each analysis step from the case study description.
Time-dependent components from 3-level nested design

Pool repeatability standard deviations for:

  1. Run 1

  2. Run 2

    Compute level-2 standard deviations for:

  3. Run 1

  4. Run 2

  5. Pool level-2 standard deviations

  6. Compute level-3 standard deviations
Database of measurements with probe #2362
  1. The repeatability standard deviation is 0.0658 for run 1 and 0.0758 for run 2. This represents the basic precision of the measuring instrument.

  2. The level-2 standard deviation pooled over 5 wafers and 2 runs is 0.0362 This is significant in the calculation of uncertainty.

  3. The level-3 standard deviation pooled over 5 wafers is 0.0197 This is small compared to the other components but is included in the uncertainty calculation for completeness.
Bias due to probe #2362
  1. Plot biases for 5 NIST probes

  2. Compute wafer bias and average bias for probe #2362

  3. Correction for bias and standard deviation
Database of measurements with 5 probes
  1. The plot shows that probe #2362 is biased low relative to the other probes and that this bias is consistent over 5 wafers.

  2. The bias correction is the average bias = 0.0393 over the 5 wafers. The correction is to be subtracted from all measurements made with probe #2362.

  3. The uncertainty of the bias correction = 0.0051 is computed from the standard deviation of the biases for the 5 wafers.
Bias due to wiring configuration A
  1. Plot differences between wiring configurations

  2. Averages, standard deviations and t-statistics
Database of wiring configurations A and B
  1. The plot of measurements in wiring configurations A and B shows no difference between A and B.

  2. The statistical test confirms that there is no difference between the wiring configurations.
  1. Standard uncertainty, df, t-value and expanded uncertainty
Elements of error budget
  1. The uncertainty is computed from the error budget. The uncertainty for an average of 6 measurements on one day with probe #2362 is 0.078 with 42 degrees of freedom.
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