Stat 2 - Homework 2
Name: _ SID: _ GSI: _
1) True or False
a. A histogram allows you to visualize how values are distributed. True
b. Bars in a histogram can be rearranged. False
c. The area of the bars in a histogram represent the frequency of values in
Stat 2 - Practice Test
1) In a study of blood pressure and number of children, it turns out that there is a strong positive correlation
between blood pressure and how many children they have. True or False:
a. People with high blood pressure tend to have
Solution to Midterm 2 material and Chap 27, 28 review problems
Midterm 2 material
What is the probability that Stan finishes second?
Soln: The chance Stan finishes second depends on who finishes first you
Solutions to Final Exam Review Chap 21, 23, 26 and Midterm 1 material:
Midterm 1 material:
Problem 3. Central Limit Theorem (CLT) , draw from highly non normal box:
For each of the following, indicate the distribu
Elizabeth Wu
May 3rd, 2015
Review Sheet : Chapter 27 and 28
Chapter 27: More Tests for Averages
1. The Standard Error for a Difference
The standard error for the difference of two independent quantities is:
where,
a = SE for the first quantity
b = SE fo
Assignment #12
Pg. 187 #3 Person B will have a smaller rms error. (1-r^2)= [1-(0.6)^2]= 0.8. It will be
smaller by 0.8.
Pg. 198 #3 Answers: a) 38% (in the first picture), b) 59% (in the second picture)
#1 page 198
The rms error of reg line for predicting
1
Chapter 27: Two sample Tests
Recall the process of how to conduct two sample tests: (hypothesis testing)
1. Find the null and alternative hypothesis
a. Null- difference due to chance variation
b. Alt- difference not due to chance variation
2. Test Stati
Chapter 17-19 Review
Chapter 17
Expected Value for sum = number of draws
x
average of box
The sum of draws from a box is a random variable with a normal distribution. Its center is called
the expectation of the sum and the spread (SD) is called the standa
Midterm Review Sheet Ch. 8-12
Chapter 8:
Association:
With strong association between 2 variables, it helps when trying to predict the other.
With weak association- not much help.
Independent variable- this variable influences the dependent variable (x)
Midterm #1 Practice Questions
Chapter 1,2:
Q5) No, you cannot assume that one vet is better than the other. The case or severity of the
injury the raccoons have experienced may be different. Some raccoons may have had more
life-threatening injuries than o
Statistics 2
Chapter 1,2 Controlled Experiment and Observational Studies
Good experiment
Steps:
1. Define research question and response variable (what measuring)
2. Obtain a group of eligible study units
3. Randomly assign them to treatment group and a c
Chapter 21: Accuracy of Percentages
Statistic= parameter + chance error
Bootstrapping:
Take reasonably large sample
Pretend the sample % is population % in the box and compute SE of the % as before
Confidence Intervals- the integral captures the popula
Assignment #11
Pg. 167 #2 Answers: a) 79%, b) 38%, c)50%, d) 50%
Pg. 174 #2
No the tutoring had an effect on the final scores. The regression effect causes the numbers to be closer to the
average.
Pg. 176 #4
next problem Continued.
Pg. 178 #9 Answers: a)
Assignment #4
Pg. 27
12) As far as studying the voting behavior in the entire city as a whole, the people who registered
to vote may not vote for the same party. They may have registered as a specific party but voted
for a different candidate. An individu
1
Assignment #6
Pg. 74
3)
a. Without doing arithmetic, the average is around 5.
b. Without doing arithmetic, the SD is around 3.
Pg. 93 (pictured)
1) a. 20 scores
b. 21 scores
1)
Pg. 94
2
3) Pictured below: answers are a) 6.68% and b) 0.62%
Pg. 95
3
7) An
Assignment #13
Pg. 268
16) This is a statistic because they are making are saying similarly, the great kings
typically had prime ministers who were not as great. They are comparing it to the first
sentence, which is a fact.
Pg. 268, #17, Answer: 19.76%
Pg
1
Assignment #8
Pg. 124
6)
a. The average midterm score was around 75
b. The SD of the midterm scores was around 10.
c. The SD of the final scores was around 20.
d. The final exam was harder.
e. More spread in the final score
f. True
Pg. 128
1)
a. The cor
Assignment #9
Pg. 134- work shown below in picture #1b) Answer: r= 0.82
1b)
Pg. 143- work shown below in picture #4) Answer: Change of scales does not affect r. It stays the
same.
4)
Pg. 144
9) The bigger correlation will come from the weatherman who comp
Assignment #10
Pg. 146
2) For all the children together, the correlation would be somewhat more than 0.67. The initial
correlation separated each age from 6 to 11 so with all the data put together there will be a
stronger correlation, making it look more
Assignment #7
Pg. 104
1) False, there is always room for human error. It is impossible for human beings to perform
tasks without making an error. Humans are inherently made to make mistakes and learn
from them. The second measurement may be slightly diffe
1
Assignment #5
Pg. 65
5) The average age for registered students at universities in the U.S. would be larger.
Pg. 75
7)
a. Male average: 66kg=145.2lb
Male SD: 9kg= 19.8lb
Female average: 55kg= 121lb
Female SD: 9kg=19.8lb
b. 68%
c. Bigger than 9kg because
Assignment #2
Pg. 23 (the refused group is your control here since they aren't examined)
10a) This is not a good comparison because the rates are very close 1.1 and 1.5 is not a big
change. It is biased for screening because the number for examined (scree
Assignment #3
Pg. 24
13) False, there is a confounding variable with the amount of students that applied to the
different departments. There was a different number of people that applied to departments A and
B.
Pg. 26
7)
a. Observational study
b. Educatio
STAT 2 LECTURE 2
Experiments, continued (Chapter 1)
Observational studies (Chapter 2)
Experiments
In experiments, the experimenter
determines who gets the treatment
and how much treatment (dose).
There are good experiments and bad
experiments, better ex