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

2.6.3.3.

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: Run 1 Run 2 Compute level-2 standard deviations for: Run 1 Run 2 Pool level-2 standard deviations Compute level-3 standard deviations	Database of measurements with probe #2362 The repeatability standard deviation is 0.0658 ohm.cm for run 1 and 0.0758 ohm.cm for run 2. This represents the basic precision of the measuring instrument. The level-2 standard deviation pooled over 5 wafers and 2 runs is 0.0362 ohm.cm. This is significant in the calculation of uncertainty. The level-3 standard deviation pooled over 5 wafers is 0.0197 ohm.cm. This is small compared to the other components but is included in the uncertainty calculation for completeness.
Bias due to probe #2362 Plot biases for 5 NIST probes Compute wafer bias and average bias for probe #2362 Correction for bias and standard deviation	Database of measurements with 5 probes The plot shows that probe #2362 is biased low relative to the other probes and that this bias is consistent over 5 wafers. The bias correction is the average bias = 0.0393 ohm.cm over the 5 wafers. The correction is to be subtracted from all measurements made with probe #2362. The uncertainty of the bias correction = 0.0051 ohm.cm is computed from the standard deviation of the biases for the 5 wafers.
Bias due to wiring configuration A Plot differences between wiring configurations Averages, standard deviations and t-statistics	Database of wiring configurations A and B The plot of measurements in wiring configurations A and B shows no difference between A and B. The statistical test confirms that there is no difference between the wiring configurations.
Uncertainty Standard uncertainty, df, t-value and expanded uncertainty	Elements of error budget 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.