Preparing to Conduct a Chi-Square Test for Goodness of Fit — Quiz
Question 7 • Statistics
An employee claims that 20 percent of the email she receives is personal, 60 percent is work related, and 20 percent is spam. The high level of spam she is receiving is frustrating, so she creates some new filters. She then selects a random sample of 50 emails over the next several weeks. She would like to know if the distribution of emails she receives has changed. What are the appropriate hypotheses?
Answer
A
cap h sub 0 : The distribution of emails received is still 20 percent personal, 60 percent work related, and 20 percent spam. cap h sub A : The distribution of emails received is no longer 20 percent personal, 60 percent work related, and 20 percent spam.
B
cap h sub 0 : The distribution of emails received is still 20 percent personal, 60 percent work related, and 20 percent spam. cap h sub A : She now receives less than 20 percent spam.
C
cap h sub 0 : The distribution of emails received is still 20 percent personal, 60 percent work related, and 20 percent spam. cap h sub A : She now receives an amount different from 20 percent spam.
D
cap h sub 0 : The distribution of emails received is no longer 20 percent personal, 60 percent work related, and 20 percent spam. cap h sub A : The distribution of emails received is still 20 percent personal, 60 percent work related, and 20 percent spam.
Explanation
The null hypothesis describes the original distribution: 20% personal, 60% work related, and 20% spam. Because she wants to know whether the distribution has changed, the alternative should allow any change in those proportions, not just a decrease in spam. Thus, choice A gives the appropriate hypotheses.
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