A lawnmower manufacturer sells partially assembled lawnmowers through large hardware stores. The manufacturer typically receives a number of calls to its toll-free line from consumers who have questions about the assembly of the lawnmowers. The manufacturer wants to reduce the number of these calls, so it creates a new version of the written instructions that accompany the lawnmower. The manufacturer, working with retail outlets, randomly selects two groups of consumers: some who buy the lawnmower with the old assembly instructions, and some who buy the lawnmower with the new assembly instructions.
a. The manufacturer contacts consumers and asks them to rate the written assembly instructions, on a scale of 1 to 5, with 1 corresponding to "very easy to read and follow," and 5 corresponding to "very difficult to read and follow." Is there evidence that consumers find the new instructions easier to read and follow? Use α = 0.05.
b. The lawnmower company also asks consumers to report how long it took them to assemble their new lawnmowers (in minutes).
Is there evidence that assembly times for consumers using the new instructions are lower than for consumers using the old instructions? Use α = 4$. Is there any reason the company should be cautious in concluding the new instructions are better?