Impurities in the form of iron oxides lower the economic value and usefulness of industrial minerals, such as kaolins, to ceramic and paper-processing industries. A 24 experiment was conducted to assess the effects of four factors on the percentage of iron removed from kaolin samples (“Factorial Experiments in the Development of a Kaolin Bleaching Process Using Thiourea in Sulphuric Acid Solutions,” Hydrometallurgy, 1997: 181–197). The factors and their levels are listed in the following table:
The data from an unreplicated 24 experiment is listed in the next table.
a. Calculate estimates of all main effects and two-factor interaction effects for this experiment.
b. Create a probability plot of the effects. Which effects appear to be important?
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Probability and Statistics for Engineering and the Sciences
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