lab5f09_ans

lab5f09_ans - ANSWER KEY LAB 5 STAT 401C FALL 2009 Question...

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ANSWER KEY – LAB 5 STAT 401C – FALL 2009 Question 1 (a) 0 .05,14 0 :1 . 2 . 2 1.466 1.2 2.736 / .3765/ 15 . 7 6 1 Reject . There is not sufficient evidence to conclude that the mean mercury concentration, , has increased since the accident. a c c Hv s H Y t sn RR t t H μ ≤> −− == = >= (b) 3 .32 mg/m σ a d β Power = 1 1.28 .25 .8 .2 1.32 .375 .6 .4 1.36 .5 .4 .6 1.40 .625 .25 .75 (c) Explain (i) There is a good chance of falsely rejecting the null hypothesis if the actual increase in the mean mercury concentration is as small as .08 3 mg/m because the test has a very lower power of .20. The probability of failing to reject 0 H is (1-.20) = .80. This is a very high probability. (ii) On the other hand, there is a very good chance of rejecting 0 H if the actual increase in the mean mercury is as large as .20 3 mg/m . The test has a higher power (.75) and the probability of falsely rejecting the 0 H is .25. Therefore the statement is reasonable. (d) 0 1, 0.5, 1.44, 1.2 |1.44 1.2 | .75 .32 a d βα ≤= = = From chart in Table 3, n is approximately 20. From the table handed out in class n = 17.
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Question 2 a) 6667 . 214 9 / ) 10 / ) 1900 ( 362932 ( 2 2 1 = = s 9333 .
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This note was uploaded on 01/23/2010 for the course STAT 213 taught by Professor Hao during the Spring '10 term at Internet2.

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lab5f09_ans - ANSWER KEY LAB 5 STAT 401C FALL 2009 Question...

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