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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 multiplechoice questions).
•
Rules of uniformity: Onesided 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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View Full Document 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.
 Fall '08
 Heller
 Statistics

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