A consumer magazine polls cell-phone-users to see if they are happy with their phones and would purchase the same model again. They randomly selected cell-phone-users and found the following: 429 of 550 owners of iPhones would purchase their phone again, and 324 of 450 owners of Androids would purchase the same phone again.
A consumer magazine polls cell-phone-users to see if they are happy with their phones and
would purchase the same model again. They randomly selected cell-phone-users and found
the following: 429 of 550 owners of iPhones would purchase their phone again, and 324 of
450 owners of Androids would purchase the same phone again.
a) Check the assumptions and conditions for comparing proportions.
b) Find a 95% confidence interval (Two-Proportion z-Interval) for the difference in the
proportions.
c) Interpret your interval in the context of the problem. What does the confidence interval
say about the difference in the satisfaction of the two types of owners (hint: pay attention
to the signs on the LB & UB)?
d) Conduct a hypothesis test with an alpha-level of 0.05 to determine if there is strong
evidence that owners of iPhones are happier with their purchase than owners of
Androids. (Be sure to give the name of the test that you are performing.)
e) If your conclusion was wrong, what type of error did you make (Type I or Type II)?
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