# pat-key1 - 4 True(2 points 5(a(2 points H The coin is fair...

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STA 3024 Homework 1 Key 1. This is an observational study. We merely observe the subject’s resting heart rate without applying any sort of ”treatment” to the subjects. (3 points) 2. (a) let be event A: a voter is a female. P(A)= 2500 6500 . 385 (3 points) (b) let be event B: a subject is favorable to candidate A. P(B)= 2750 6500 . 423 (3 points) (c) The probability of interest is: P(A and B)= P ( A B ) = 1250 6500 . 192 (3 points) (d) The probability of interest is: P(A/B)= 1250 2500 = . 5 (3 points) Alternatively you could have computed it with: P(B/A)= P ( A B ) P ( A ) = 1250 6500 2500 6500 = . 5 3. The identiﬁcation of the explanatory variable and the response variable is intuitive as mentioned in class and it makes a lot more sense to think of the 2004 vote as a prediction of the 2008 vote. (a) The explanatory variable is who the person voted for in 2004. It is categorical.(3pts) (b) The response variable is who the person voted for in 2008. It is categorical.(3pts)
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Unformatted text preview: 4. True.(2 points) 5. (a) (2 points) H : The coin is fair. H a : The coin is not fair. (Also acceptable: H : The coin lands heads/tails half the time. H a : The coin does not land heads/tails half the time.) (Also acceptable: H : p or another choice of symbol = 0 . 5 . H a : p 6 = 0 . 5 . ). (b) (2 points) A type I error occurs if we conclude the coin is not fair (also acceptable: does not land heads/tails half the time) when in fact it is fair (also acceptable: lands heads/tails half the time). A type II error occurs if we conclude the coin is fair (also acceptable: lands heads/tails half the time) when in fact it is not fair (also acceptable: does not land heads/tails half the time). 6. We should fail to reject H . since the p-value is bigger than the signiﬁcance level. (3 points) Total: 30 points...
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