Chapter 10: Q.10 (page 622)
Explain why the conditions for using two-sample z procedures to perform inference about are not met in the settings
Broken crackers We don鈥檛 like to 铿乶d broken crackers when we open the package. How can makers reduce breaking? One idea is to microwave the crackers for seconds right after baking them. Breaks start as hairline cracks called 鈥渃hecking.鈥 Assign newly baked crackers to the microwave and another to a control group that is not microwaved. After one day, none of the microwave group and of the control group show checking.
Short Answer
From the given information,
The success rate in the first sample, i.e. the microwave group, is (less than ). It means that the normalcy assumption isn't met in this case.
As a result, the two-proportion z-test is inappropriate in this situation.
