An airplane manufacturer needs to purchase an aluminum alloy for use in constructing a part for their new line of jumbo jets. It
is important that the alloy be very strong. Three suppliers, A, B and C can provide this alloy. In order to make their own comparison of the alloys produced by these suppliers they obtain samples from each one and test their tensile strength. The results follow: A B C
200 psi* 177 psi 202 psi
180 167 212
190 188 214
190 180 188
190 180 188
182 * psi = pounds per square inch
What statistical test/procedure would you use to determine whether there is a significant difference in the tensile strength of the alloys produced by the three suppliers (a = .05)?
In this example, you have 3 populations determined by each aluminum alloy A, B, and C and want to test if their tensile strength is the same or not. So the study variable is the tensile strength of the aluminum and it is tested in each sample taken of each alloy. The parameters of interest are the average tensile strength of each alloy.
The best statistical procedure to compare these three population is an ANOVA test of one factor(tensile strength) with three levels (alloy A, alloy B, and alloy C)
