Analyze Factorial Design

Overview | How to | Example

 

 

Overview

This tool analyzes the factorial design to fit a model. ProcessMA generates a default set of terms to be included in the model but you can also add or remove these terms. If you have center points and blocks in the design, you can also choose to model center points and block effects respectively. This tool also allows you to generate effects plots and residual plots to assess model adequacy. The residuals and fitted values of the response are shown in Columns AA:AB.

ProcessMA will only be able to analyze designs that it creates. If you need to analyze existing design, you need to recreate the design matrix.

 

 

How to

At the Excel Menu (For Excel 2007, go to Add-ins first)

  1. Choose ProcessMA > DOE > Create Factorial Design

  2. In Response, select the column containing the response data (Numeric)

  3. Under Terms Tab, in Maximum Order of Terms, choose the maximum order of terms to include in the model

  4. Under Terms Tab, in Available Terms, double-click on any terms to include it in the model

  5. Under Terms Tab, in Selected Terms, double-click on any terms to exclude it from the model

  6. Under Terms Tab, check Include Center Points, if you want to include center points in the analysis

  7. Under Terms Tab, check Include Blocks, if you want to include blocking in the analysis

  8. Under Results Tab, check Plot Residuals, to display the residual plot

  9. Under Results Tab, check Show Pareto Plot of Effect, to display a Pareto chart of the effects

  10. Under Results Tab, in Alpha, enter the level used to determine the significance of the effects (Numeric, >0 & <1)

  11. Click OK

 

 

Example

You want to investigate how temperature, intensity of light and type of catalyst affect the growth of organisms. You created a full factorial design for three factors and with three replicates. You ran the experiments and recorded the data.

  1. Refer to Create Factorial Design help file to create a design for analysis

  2. Choose ProcessMA > DOE > Analyze Factorial Design

  3. In Response, select H - Response

  4. Under Results Tab, check Show Pareto Plot of Effect

  5. Click OK

 

Results & Interpretation

From p values in the analysis of variance table, it suggests that the main effects and the 2-way interaction are significant while the 3-way interaction is not. From the p values in the estimated effects and coefficients, it suggests that only the two main effects (Temp and Light) and the 2-way interaction (Temp*Light) are significant.

 

 

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