STATISTICS 151 SECTION 2 MIDTERM 1
OCTOBER 3 2006
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This is an open book exam. Course text, personal notes and ca

STOR 151 SECTION 2 MIDTERM 2
MARCH 25 2010
This is an open book exam. Course text, personal notes and calculator are permitted. You
have 75 minutes to complete the test. Personal computers and cellphones are not to be used during
the exam. If you have any

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CHAPTER 4:
GATHERING DATA
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Experiments and Observational Studies
Recall basic denitions:
Population
Sample
Response variable
Explanatory variable
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Example 1. A clinical trial is set up to compare a proposed new
drug with a placebo (some iner

One place the calculation of is useful is in considering the value
of insurance policies.
Example: The actuary for an insurance company determines that
you have a 5% chance in any one year of requiring repair damage
to your car, which we will simplify by

The Binomial Distribution
Example. Suppose we have a large number of cards each marked
with one of the letters A,B,C,D,E. I draw ve cards (independently) from this deck and ask someone to guess which letter is
on each of them. What is the probability that

HW3, due 2/04/10: 2.110, 2.120, 2.128, 3.46
Note: question 2.128 asks you to download some data on baseball home runs from the course CD, and use the techniques of
this course to determine which one was the best. Obviously there
is no unique correct answe

Homework 7, Due March 18 2010
Chapter 6, questions 6.6, 6.10, 6.26, 6.28
Remark: 6.28 is a follow-on to 6.27. You are not requested to
hand in 6.27 as well, but probably you should work through 6.27
for yourself, before tackling 6.28.
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Here is another ex

Sample and Populations
The population is the set of subjects in which we are interested.
The sample is the subset of the population for whom we have
(or plan to have) data.
Examples:
General Social Survey (GSS): sample 4510, population all
adult American

STOR 151 SECTION 2 FINAL EXAM
MAY 1 2010
YOUR NAME:
PID:
Honor pledge: On my honor, I have neither given nor received unauthorized aid in this exam.
SIGNATURE:
Please write your answers in a blue book, except for the graph in Question 2 which is at the
en

STOR 151 SECTION 2 MIDTERM 1
FEBRUARY 18 2010
This is an open book exam. Course text, personal notes and calculator are permitted. You
have 75 minutes to complete the test. Personal computers and cellphones are not to be used during
the exam. If you have

Angel Choe
1.4
a) The histogram allows a view of how many people finished the marathon at a certain time, while
the box plot doesnt specify how many people but rather allows the viewer to estimate how many
winners there are. The box plot allows a view of

Angel Choe
4.9
a) There is a relationship between the data for 1968 and 2008 because the 51 recorded
temperatures in January were from the same locations for both 1968 and 2008 meaning that they
are paired.
b) Ho : diff = 0 The null hypothesis is that the

Angel Choe
3.2
b) P = 0.77 n(p) 10 n(1-p) 10 n = 40, p = 0.77 np = 40*0.77 = 30.8
n(1-p) = 40*0.23 = 9.2 10 so not relatively normal, so the statement
is false
c) False, because 85% is in two standard deviations of p, meaning that the data would not
need

Angel Choe
1.4
a) The histogram allows a view of how many people finished the marathon at a certain time, while
the box plot allows a view of the median of the data.
b) A reason for the bimodal distribution may be because the data accounts both female and

Angel Choe
3.14
a) H0: p = 0.5 HA: p > 0.5 z = .56-.5/ z = 0.6/ 1.288E-2 z = 4.66, p value is 1.58E-6, so
the null hypothesis can be rejected because the p value is so negligibly small, meaning the data
does not provide strong evidence that a majority of

Angel Choe
1.2
A) 66/85 = 0.78 = 78% of patients that received treatment experienced a significant
improvement in symptoms. 65/81 = 0.80 = 80% of patients that received the placebo
experienced a significant improvement in symptoms
B) Both treatments were

Angel Choe
1.12
a) There is a positive association between life expectancy and % of internet users based
on the data provided.
b) This is an observational study because of there being no control and experimental
group.
c) A possible confounding variable w

Homework 8, Due March 25 2010
Chapter 6 (pages 299301): 6.36, 6.38, 6.42, 6.44
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P (x) =
n!
px(1 p)nx.
x!(n x)!
This formula is known as the binomial distribution. The essential
conditions for a binomial distribution are:
1. Each outcome of the experiment

HW9, due April 8:
questions 8.14, 8.22, 8.32 and 8.38
(pages 372-373 and 383-384)
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Condence intervals for a population mean
So far we have talked about condence intervals only in the case
of a sample proportion. What about the other case covered in
Chapt

Determining the sample size
One of the most common questions any statistician gets asked
is How large a sample size do I need? Researchers are often
surprised to nd out that the answer depends on a number of
factors and they have to give the statistician

HW10, due April 15 2011:
8.48, 8.52, 9.14, 9.16 (pages 384 and 426)
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Testing Hypotheses
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Motivating discussion
A newspaper story discussed the possible increase of skin cancer
in marathon runners, based on a paper Malignant melanoma
in marathon runner

Point and Interval Estimates
Suppose we want to estimate a parameter, such as p or , based
on a nite sample of data. There are two main methods:
1. Point estimate: Summarize the sample by a single number
that is an estimate of the population parameter;
2.

Side comment: In this example, we dont actually know that
p = 0.68 is the correct value for the whole population thats
only an estimate based on the sample. But the value of the
standard error is not all that sensitive to p for example, it
would be 0.0136

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Statistics is the art and science of designing studies and analyzing the data that those studies produce. Its ultimate goal is
translating data into knowledge and understanding of the world
around us. In short, statistics is the art and science

Describing Data Using Graphical
Summaries
1. Categorical Data
2. Quantitative Data
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Graphs for Categorical Variables
Pie charts
Bar graphs
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Pie chart for party aliation (2009) (35D, 12I, 21R)
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Pie chart for party aliation (2010) (26D, 13I, 42R)
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Seg

Review of Last Class: Testing a Proportion
Suppose the data are a sample proportion p from the sample
of size n where the true population proportion is an unknown
quantity p. The null hypothesis is
H0 : p = p 0
where p0 is some given proportion.
The alter

Homework 11, due April 22 2010.
9.32, 9.36 (page 440)
10.6, 10.12 (pages 480/481)
Note: In 10.6, dont just take the 95% CI for dierence and
the Test for dierence as given: show how they were derived.
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Question 9.79, page 462.
For a quantitative variable

Angel Choe
1.
A) There are 10 variables.
B) Categorical variables are name and state. Numerical variables are population of 2000, population
of 2010, federal spending, poverty, homeownership, multiple units, income, and medical income.
C) Command tail sho