stat101-midterm-solution

Stat101-midterm-solu - MIDTERM EXAM STAT 101 Instructor A Rakhlin Student Name Section Instructions Use the space provided to answer questions You

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MIDTERM EXAM STAT 101, Instructor: A. Rakhlin October 27, 2011 Student Name: Section: Instructions Use the space provided to answer questions. You can use the back of these pages as scratch paper. You must show work and give explanations (except for the multiple-choice questions). Rules of uniformity: One-sided letter crib sheet, calculator ok (even with statistical functions and graphing), otherwise closed notes, closed book. No cell phones visible! Rules of Fairness: Complete this exam entirely on your own. Do not acquire information from other stu- dents or the outside in any form. Do not take copies of this exam out of this room. You have two hours for this exam. Any student observed continuing to write after time has been called will be documented and points will be deducted. Rules of Consideration: Be considerate to others by not causing commotion and distraction. If you finish early, leave quietly; avoid slamming doors. Honor code applies to the above Rules. Your signature: About this test: When more than one choice seems reasonable, pick the one that is best. STOP WAIT UNTIL YOU ARE INSTRUCTED TO PROCEED. 20 questions for a total of 100 points.
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STAT 101 Midterm Exam 1. (3 points) Histograms . .. (a) are the same as bar plots (b) look very similar to bar plots but show binned quantitative variables instead (c) are more useful for qualitative variables than bar plots (d) none of the above Answer: B. A histogram is a plot of distribution of a numerical (quantitative) variable as counts of occur- rences within adjacent intervals (bins). 2. (3 points) Mosaic plots are best for . .. (a) showing proportions of the values of a qualitative variable (b) comparing counts of the values of one qualitative variable conditional on the values of another qualitative variable (c) comparing proportions of the values of one qualitative variable conditional on the values of another qualitative variable (d) comparing the dispersion of two qualitative variables Answer: C. 3. (3 points) The removal of an outlier with a z -score of - 2 . 1 causes (a) the mean of the data to increase and the standard deviation of the data to decrease (b) the mean of the data to increase and the standard deviation of the data to increase (c) the mean of the data to decrease and the standard deviation of the data to decrease (d) the mean of the data to decrease and the standard deviation of the data to increase Answer: A. When we remove an outlier with z score - 2 . 1, the mean of the data should increase because we remove a number of very small value. The standard deviation increases. 4. (2 points) (T/F) Association between two categorical variables can be verified by comparing their bar charts.
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This note was uploaded on 04/04/2012 for the course STAT 101 taught by Professor Heller during the Fall '08 term at UPenn.

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Stat101-midterm-solu - MIDTERM EXAM STAT 101 Instructor A Rakhlin Student Name Section Instructions Use the space provided to answer questions You

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