Mixture Design Tutorials - Statease.info

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The next step in the process is to analyze the data. Begin the analysis phase by clicking on the node for Viscosity (to left of window). First Step in the Analysis: Transformation Dialog Box You now will work across the buttons at the top of the window. First, consider doing a transformation on the response. In some cases this will improve the statistical properties of the analysis. For example, when responses vary over several orders of magnitude, the log scale usually works best. For this data, leave the selection at its default, None, because no transformation will be needed. Click on the Fit Summary button next. At this point Design-Expert fits linear, quadratic, special cubic and full cubic polynomials to the response. Fit Summary Table: Sequential Model Sum of Squares 7-10 • Mixture Design Tutorials Design-Expert 6 User’s Guide
Rev. 5/10/02 You may need to widen your window to get the entire output showing. Just move the cursor to the left edge until it changes to a double-ended arrow. Then drag it open. In similar fashion, you can also adjust column widths in any table or report. This may be necessary to uncover the entire text. To move around the display, use the side and/or bottom scroll bars, if necessary. First, look for any warnings about aliasing. In this case, the full cubic model could not be estimated by the chosen design - an augmented simplex design. Remember that you chose only to fit a quadratic model, so this should be no surprise. Next, you see the “Sequential Model Sum of Squares” table. The analysis proceeds from a basis of the mean response. This is the default model if none of the factors cause a significant effect on response. The output then shows the significance of each set of additional terms: • “Linear”: the significance of adding the linear terms after accounting for the mean. (Due to the constraint that the three components must sum to a fixed total, you will see only two degrees of freedom associated with the linear mixture model.) • “Quadratic”: the significance of adding the quadratic terms to the linear terms already in the model. • “Special Cubic”: the contribution of the special cubic terms beyond the quadratic and linear terms. • “Cubic”: the contribution of the full cubic terms beyond the special cubic, quadratic, and linear terms. (In this case, these terms are aliased.) For each set of terms, the probability (“Prob > F”) should be examined to see if it falls below 0.05 (or whatever statistical significance level you choose). Adding terms up to quadratic will significantly improve this particular model, but when you get to the special cubic level, there’s no further improvement. The program automatically underlines at least one “Suggested” model. Always confirm this suggestion by reviewing all the tables under Fit Summary. See the on-line Help system for more information about the procedure for choosing model(s). Scroll down to see if the quadratic model adequately fits the data. Fit Summary Table: Lack of Fit Tests Design-Expert 6 User’s Guide Mixture Design Tutorials • 7-11
Page 1 and 2: Section 7 - Mixture Design Tutorial
Page 3 and 4: Rev. 5/10/02 and High fields, press
Page 5 and 6: Save the Data to a File Rev. 5/10/0
Page 7 and 8: Edit the Design Notice that the rea
Page 9: Analyze the Results Rev. 5/10/02 Op
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Page 15 and 16: Review Diagnostic Graphs Diagnostic
Page 17 and 18: Trace Plot Contour Plots Select Vie
Page 19 and 20: Incremental Option for Contour Leve
Page 21 and 22: Standard Error Plot Rev. 5/10/02 No
Page 23 and 24: Analyze the Data for the Second Res
Page 25 and 26: Numerical Optimization Rev. 5/10/02
Page 27 and 28: These settings create the following
Page 29 and 30: shown. Likewise, moving the bar to
Page 31 and 32: Rev. 5/10/02 you view the 3D surfac
Page 33 and 34: Rev. 5/10/02 The high resolution ma
Page 35 and 36: Rev. 5/10/02 Select POE (Turbidity)
Page 37 and 38: Setting Criteria for Graphical Opti

Mixture Design Tutorials - Statease.info

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