pracfinalfall2011

pracfinalfall2011 - Practice Final; Statistics 371; Fall...

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Practice Final; Statistics 371; Fall 2011; Professor Wardrop Below are selected values of t for Gosset’s 95% intervals. If you cannot Fnd the t you need below, use z =1 . 96 . df: 6 7 8 9 10 11 12 13 14 15 t :2 . 4 4 7 2 . 3 6 5 2 . 3 0 6 2 . 2 6 2 2 . 2 2 8 2 . 2 0 1 2 . 1 7 9 2 . 1 6 0 2 . 1 4 5 2 . 1 3 1 df: 16 17 18 19 20 21 22 23 24 25 t . 1 2 0 2 . 1 1 0 2 . 1 0 1 2 . 0 9 3 2 . 0 8 6 2 . 0 8 0 2 . 0 7 4 2 . 0 6 9 2 . 0 6 4 2 . 0 6 0 Problems 1–2 are about Simpson’s Paradox. In each problem you are given a collapsed table and two partially completed component tables for it. In each of these problems Fnd all pairs of values of c and d so that Simpson’s Paradox is occurring or explain why Simpson’s Paradox cannot occur for these data. You must present computations to justify your answer. Make sure to label which number is c and which is d . 1. The collapsed table is below. Group SF Total 11 0 2 1 9 8 3 0 0 28 9 1 6 1 2 5 0 191 359 550 The component tables are below. Subgp A Subgp B Gp Tot Gp 16 0 1 4 0 2 0 0 14 2 5 8 1 0 0 2 c 100 2 d 150 300 250 2. The collapsed table is below. Group 7 8 3 1 3 0 24 2 5 8 1 0 0 89 141 230 The component tables are below. Subgp A Subgp B Gp Gp 12 1 5 47 5 6 2 95 5 2 c 35 2 d 65 110 120 3. In the 1983 Wisconsin Survey of drivers, 40.7% of 450 females responded ‘Ex- tremely serious’ to the question How serious a problem do you think drunk driving is in Wis- consin? In addition, 36.4% of 538 males gave the same answer to this question. Compare the implied populations with a 95% conFdence interval. Carefully state your assumptions. 4. Refer to the previous question. The sub- jects were asked: If you are arrested for drunken driving, what are your chances of being convicted? Of the 446 females, 17.3% answered ‘very high;’ of the 537 males 25.7% answered ‘very high.’ Compare the implied populations with an 95% conFdence interval. Carefully state your assumptions. 1
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5. I have drawn a histogram for 500 obser- vations. One of the rectangles has end- points of 1.00 and 3.00, and a height of 0.20. For each of the three situations be- low, determine how many observations are in this class interval [1.00 to 3.00), with the usual endpoint convention. (a) If it is a frequency histogram. (b) If it is a relative frequency histogram. (c) If it is a density scale histogram. 6. I have drawn a histogram for 800 obser- vations. One of the rectangles has end- points of 0.20 and 0.30, and a height of 5. For each of the three situations below, de- termine how many observations are in this class interval [0.20 to 0.30), with the usual endpoint convention. (a) If it is a frequency histogram. (b) If it is a relative frequency histogram. (c) If it is a density scale histogram. 7. I observed 50 i.i.d. trials. Below are my 50 sorted observations. 0.02 0.04 0.14 0.18 0.32 0.44 0.46 0.68 0.86 1.04 1.06 1.26 1.32 1.38 1.42 1.50 1.54 1.56 1.60 1.74 2.26 2.40 2.58 2.62 2.72 2.94 3.26 3.38 3.54 3.56 3.76 3.80 3.94 4.34 4.56 5.06 5.50 5.90 6.02 6.08 6.20 6.52 6.84 8.52 8.60 10.00 10.42 10.84 x (49) 11.86 (a) Draw a density scale histogram of these data. Use 0.00–2.00, 2.00–6.00, and 6.00–12.00 as your class inter- vals. Clearly label the height and end- points of each of the rectangles.
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This note was uploaded on 12/10/2011 for the course STATS 371 taught by Professor Hanlon during the Fall '11 term at Wisconsin.

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pracfinalfall2011 - Practice Final; Statistics 371; Fall...

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