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
- A suburban hotel derives its revenue from its hotel and restaurant operations. Theowners are interested in the relationship between the number of rooms occupied on anightly basis and the revenue per day in the restaurant. Below is a sample of 25 days(Monday through Thursday) from last year showing the restaurant income and numberof rooms occupied.arrow_forwardAn article23 summarized results from the Nurses’ Health Study and the Health Pro- fessionals Follow-Up Study. The article reported (with RR = relative risk) that “Com- pared with nonregular use, regular aspirin use was associated with lower risk of overall cancer (RR 0.97; 95% CI 0.94, 0.99), which was primarily due to a lower incidence of gastrointestinal cancers, especially colorectal cancers (RR 0.81; 95% CI 0.75, 0.88).” Identify the response variables and the explanatory variable for these two results. Explain how to interpret the confidence interval about colorectal cancers. Would the association with overall cancer be considered (i) significant or non- significant? (ii) strong or weak? Explain. question 1 and 2arrow_forwardA study was performed on 200 elementary school students to investigate whether regular Vitamin A supplementation was effective in preventing colds during the month of March. 100 were randomized to receive daily Vitamin A supplements during the month of March, and 100 students were randomized to a placebo group (and did not receive Vitamin A) during the same month. The number of students getting at least one cold in March was computed in the two groups, and the results are given in the following 2 X 2 table. Using a 5% level of significance determine whether there is an association between Vitamin A supplementation and prevention of Common Cold ColdNo Cold Vitamin A1585100 Placebo2575100 40160200arrow_forward
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