Question: The Cordage Institute, based in Wayne, Pennsylvania, is an international association of manufacturers, producers, and resellers of cordage, rope, and twine. It is a not-for-profit corporation that reports on research concerning these products. Although natural fibers like manila, sisal, and cotton were once the predominant rope materials, industrial synthetic fibers dominate the marketplace today, with most ropes made of nylon, polyester, or polypropylene. One of the principal traitsof rope material is its breaking strength. A research project generated data given in the file titled Knots. The data listed were gathered on 10 different days from 1 2″-diameter ropes.
a. Test to determine if inserting the day on which the testing was done was necessary. Use a significance level of 0.05.
b. Based on the data gathered by the Cordage Institute, can it be concluded that there is a difference in the average breaking strength of nylon, polyester, and polypropylene?
c. If you concluded that there was a difference in the average breaking strength of the rope material, use Fisher's LSD approach to determine which material has the highest breaking strength.