Mt. Jumbo Plywood Company makes plywood for use in furniture production. The first major step in the plywood process is the peeling of the logs into thin layers of veneer. A lathe that rotates the logs through a knife that peels the log into layers 3/8-inch thick conducts the peeling process. Ideally, when a log is reduced to a 4-inch core diameter, the lathe releases the core and a new log is loaded onto the lathe. However, a problem called “spinouts” occurs if the lathe kicks out a core that has more than 4 inches left. This wastes wood and costs the company money.
Before going to the lathe, the logs are conditioned in a heated water-filled vat to warm them. The company is concerned that improper log conditioning may lead to excessive spinouts. Two factors are believed to affect the core diameter: the vat temperature and the time the logs spend in the vat prior to peeling. The lathe supervisor has recently conducted a test during which logs were peeled at each combination of temperature and time. The sample data for this experiment are in the data file called Mt Jumbo. The data are the core diameters in inches.
a. Based on the sample data, is there an interaction between water temperature and vat hours? Test using a significance level of 0.01. Discuss what interaction would mean in this situation. Use a p -value approach.
b. Based on the sample data, is there a difference in mean core diameter at the three water temperatures? Test using a significance level of 0.01.
c. Do the sample data indicate a difference in mean core diameter across the three vat times analyzed in this study? Use a significance level of 0.10 and a p -value approach.