Paint used for marking lanes on highways must be very durable. In one trial paint from four different suppliers, labeled GS, FD, L, and ZK, were tested on six different highway sites, denoted 1, 2, 3, 4, 5, .6. After a considerable length of time, which included different levels of traffic and weather, the average wear for the samples at the six sites was as follows:
The objective was to compare the wear of the paints from the different suppliers.
(a) What kind of an experimental design is this'?
(b) Take a graphical analysis and an ANOVA.
(c) Obtain confidence limits for the supplier averages.
(d) Make checks that might indicate departures from assumptions.
(e) Do you think these data contain bad values?
(f) What can you say about the relative resistance to wear of the four paints?
(g) Do you think this experimental arrangement was helpful?