ISE 225 Engineering Statistics Homework 6 Spring 2015

ISE 225 Engineering Statistics Homework 6 Spring 2015 Due date November 12, 2015. Submit a written report with the answers for the following problem. Use a wordprocessor for the report and Minitab for conducting the statistical analysis (number the pages) Detergent manufacturers frequently make claims about the effectiveness of their products. A consumer protection service decided to test the five best-selling brands of detergent, where each manufacturer claims that its product produces the whitest whites in all water temperatures. The experiment was conducted in the following way. One hundred fifty white sheets were equally soiled. Thirty sheets were washed in each brand, l0 with cold water, 10 with warm water, and 10 with hot water. After washing, the whiteness scores for each sheet were measured with laser equipment. Use data set detergent.xls on blackboard to answer the following a) Compare box plots for each treatment. What comments (about the populations) do you have from examining these plots. b) Obtain residuals from the ANOVA test (do not make conclusions about the ANOVA test until assumptions are verified). c) Analyze the residuals from this experiment. If outliers are found identify from which treatment they come from. d) Conclude about ANOVA assumptions (use pvalues from appropiate tests) e) Conclude about ANOVA test. If this test rejects Ho: treatments means are equal, build 95% confidence intervals on the mean difference between the treatments of interest. Group the treatments and identify which treatment group would you prefer?