1. A researcher wants to determine whether geographic distance from a hospital at the time of a heart attack is related to the likelihood of surviving the heart attack. The research suspects that far distance is related to low likelihood of survival, that medium distance is related to moderate likelihood of survival, and that close distance is related to high likelihood of survival. What are the null and alternate hypotheses? What does a high chi-square value mean? What does it mean to reject the null hypothesis?
2. Looking over the results of a nationwide survey of retail customers who have shopped for clothing in the last six months (n = 150,000), an apparel brand manufacturer finds that every categorical variable has a statistically significant relationship with every other categorical variable. What can the brand manager do to make sense out of this survey?
3. Is it necessary to normalize a database? Why or why not?
4. Do you always have to use the third normal form? Why or why not? What can happen if you do not use the third normal form?
5. Normalize the following relations to 3NF, using the set of functional dependencies listed:
R1(ABCDEFGH)
FDs: ABC —> D, B —> E, A —> F, C —> GH
R2(ABCDEFGH)
FDs: AB —> CF, C —> DE, F —> G, G —> H
R3(ABCDEFGH)
FDs: ABC —> E, E —> F, C —> DE, B —> GH
You should assume that there are no duplicate rows present and that all values are atomic. Your submission should clearly identify the steps required to normalize the relation to 3NF and demonstrate that the solution is lossless and preserves all functional dependencies