Polyethylene terephthalate PET bottles are used for carbonated beverages A
Polyethylene terephthalate (PET) bottles are used for carbonated beverages. A criti cal property of PET bottles is their bursting strength (i.e., the pressure at which bottles filled with water burst when pressurized). In the Journal of Data Science (May 2003), researchers measured the bursting strength of PET bottles made from two different designs: an old design and a new design. The data (in pounds per square inch) for 10 bottles of each design are shown in the accompanying table and saved in the PET file. Suppose you want to compare the distributions of bursting strengths for the two designs.
a. Rank all 20 observed pressures from smallest to largest, and assign ranks from 1 to 20.
b. Sum the ranks of the observations from the old design.
c. Sum the ranks of the observations from the new design.
d. Compute the Wilcoxon rank sum statistic.
e. Carry out a nonparametric test (at a = .05 ) to com pare the distribution of bursting strengths for the two designs.
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