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18. You choose an alpha level of .01 and then analyze your data.
a. What is the probability that you will make a Type I error given that the null hypothesis is true?
b. What is the probability that you will make a Type I error given that the null hypothesis is false?
7. Below are data showing the results of six subjects on a memory test. The three scores per
subject are their scores on three trials (a, b, and c) of a memory task. Are the subjects get- ting
better each trial? Test the linear effect of trial for the data.
a. Compute L for each subject using the contrast weights -1, 0, and 1. That is, compute (-1)(a) +
(0)(b) + (1)(c) for each subject.
b. Compute a one-sample t-test on this column (with the L values for each subject) you created.
a b c
4 6 7
3 7 8
2 8 5
1 4 7
4 6 9
2 4 2
13. You are conducting a study to see if students do better when they study all at once or in
intervals. One group of 12 participants took a test after studying for one hour continuously. The
other group of 12 participants took a test after studying for three twenty minute sessions. The first
group had a mean score of 75 and a variance of 120. The second group had a mean score of 86
and a variance of 100.
a. What is the calculated t value? Are the mean test scores of these two groups significantly
different at the .05 level?
b. What would the t value be if there were only 6 participants in each group? Would the scores be
significant at the .05 level?
4. Rank order the following in terms of power.
Population 1
Mean n
Population 2
Mean
Standard
Deviation
a 29 20 43 12
b 34 15 40 6
c 105 24 50 27
d 170 2 120 10
65. Previously, an organization reported that teenagers spent 4.5 hours per week, on average, on
the phone. The organization thinks that, currently, the mean is higher. Fifteen randomly chosen
teenagers were asked how many hours per week they spend on the phone. The sample mean was
4.75 hours with a sample standard deviation of 2.0. Conduct a hypothesis test. The null and
alternative hypotheses are:
a. Ho: x
̄= 4.5, Ha : x
̄> 4.5
b. Ho: μ ≥ 4.5, Ha: μ < 4.5
c. Ho: μ = 4.75, Ha: μ > 4.75
d. Ho: μ = 4.5, Ha: μ > 4.5
71. Previously, an organization reported that teenagers spent 4.5 hours per week, on average, on
the phone. The organization thinks that, currently, the mean is higher. Fifteen randomly chosen
teenagers were asked how many hours per week they spend on the phone. The sample mean was
4.75 hours with a sample standard deviation of 2.0. Conduct a hypothesis test, the Type I error is:
e. to conclude that the current mean hours per week is higher than 4.5, when in fact, it is higher
f. to conclude that the current mean hours per week is higher than 4.5, when in fact, it is the same
g. to conclude that the mean hours per week currently is 4.5, when in fact, it is higher
h. to conclude that the mean hours per week currently is no higher than 4.5, when in fact, it is not
higher
i. 77. An article in the San Jose Mercury News stated that students in the California state
university system take 4.5 years, on average, to finish their undergraduate degrees.
Suppose you believe that the mean time is longer. You conduct a survey of 49 students
and obtain a sample mean of 5.1 with a sample standard deviation of 1.2. Do the data
support your claim at the 1% level?
80. At Rachel’s 11th birthday party, eight girls were timed to see how long (in seconds) they
could hold their breath in a relaxed position. After a two-minute rest, they timed themselves while
jumping. The girls thought that the mean difference between their jumping and relaxed times
would be zero. Test their hypothesis.
RElaxed time (seconds) Jumping time (seconds)
26 21
47 40
30 28
22 21
Table 10.24
91. A powder diet is tested on 49 people, and a liquid diet is tested on 36 different people. Of
interest is whether the liquid diet yields a higher mean weight loss than the powder diet. The
powder diet group had a mean weight loss of 42 pounds with a standard deviation of 12 pounds.
The liquid diet group had a mean weight loss of 45 pounds with a standard deviation of 14
pounds.
120. A golf instructor is interested in determining if her new technique for improving players’
golf scores is effective. She takes four new students. She records their 18-hole scores before
learning the technique and then after having taken her class. She conducts a hypothesis test. The
data are as follows.
Player 1 Player 2 Player 3 Player 4
Mean score before
class 83 78 93 87
Mean score after
class 80 80 86 86
Cost per
ounce
16 3.99
32 4.99
64 5.99
200 10.99
Table 12.31
82.
What is the slope of the least-squares (best-fit) line? Interpret the slope.
83.
a. Complete Table 12.31 for the cost per ounce of the different sizes.
b. Using “size” as the independent variable and “cost per ounce” as the dependent
variable, draw a scatter plot of the data.
c. Does it appear from inspection that there is a relationship between the variables?
Why or why not?
d. Calculate the least-squares line. Put the equation in the form of: ŷ= a + bx
a. Using “size” as the independent variable and “cost” as the dependent variable,
draw a scatter plot.
b.Does it appear from inspection that there is a relationship between the variables?
Why or why not?
c. Calculate the least-squares line. Put the equation in the form of: ŷ= a + bx
d. Find the correlation coefficient. Is it significant?
e. If the laundry detergent were sold in a 40-ounce size, find the estimated cost.
f. If the laundry detergent were sold in a 90-ounce size, find the estimated cost.
g. Does it appear that a line is the best way to fit the data? Why or why not?
h. Are there any outliers in the given data?
i. Is the least-squares line valid for predicting what a 300-ounce size of the laundry
detergent would you cost? Why or why not?
j. What is the slope of the least-squares (best-fit) line? Interpret the slope.
9. Can a coefficient of determination be negative? Why or why not?
8. Use the following information to answer the next twelve exercises: Suppose an
airline claims that its flights are consistently on time with an average delay of at
most 15 minutes. It claims that the average delay is so consistent that the variance is
no more than 150 minutes. Doubting the consistency part of the claim, a disgruntled
traveler calculates the delays for his next 25 flights. The average delay for those 25
flights is 22 minutes with a standard deviation of 15 minutes.
A. Let α = 0.05 Decision: ________Conclusion (write out in a complete sentence.):
________
7. above information: 113. df = ________
6. Do men and women select different breakfasts? The breakfasts ordered by
randomly selected men and women at a popular breakfast place is shown in Table.
Conduct a test for homogeneity at a 5% level of significance.
French
Toast
Pancak
es
Waffl
es
Omelett
es
Men 47 35 28 53
Wom
en
65 59 55 60
5. The standard deviation of the chi-square distribution is twice the mean.
True/false.
4. Is there evidnce of association between color and texture for these limestones?
Explain. Light Medium Dark
Fine 4 20 8
Medium 5 23 12
Coarse 21 23 4
2. For the X,Y data below, compute:
a. r and determine if it is significantly different from zero.
b. the slope of the regression line and test if it differs significantly from zero.
c. the 95% confidence interval for the slope.
1. The formula for a regression equation is Y’ = 2X + 9.
a. What would be the predicted score for a person scoring 6 on X?
b. If someone’s predicted score was 14, what was this person’s score on X?
1. If an experiment is conducted with 5 conditions and 6 subjects in each condition, what
are dfn and dfe?
3 AT) The dataset ADHD Treatment has four scores per subject.
a. Is the design between-subjects or within-subjects?
b. Create an ANOVA summary table.
4. AT) Using the Anger Expression Index from the Angry Moods study as the dependent
variable, perform a 2x2 ANOVA with gender and sports participation as the two factors.
Do athletes and non-athletes differ significantly in how much anger they express? Do the
genders differ significantly in Anger Expression Index? Is the effect of sports
participation significantly different for the two genders?
5.
Northe
ast
Sout
h West Cent
ral East
16.3 16.9 16.4 16.2 17.1
16.1 16.5 16.5 16.6 17.2
16.4 16.4 16.6 16.5 16.6
16.5 16.2 16.1 16.4 16.8
degrees of freedom – numerator: df(num) = _________
6. F statistic = ________
7. A researcher wants to know if the mean times (in minutes) that people watch
their favorite news station are the same. Suppose that Table 13.24 shows the
results of a study.
C
N
N
F
O
X
Loc
al
45 15 72
12 43 37
18 68 56
38 50 60
23 31 51
35 22
8. re the mean number of times a month a person eats out the same for whites,
blacks, Hispanics and Asians? Suppose that Table 13.26 shows the results of a
study.
Whi
te
Blac
k
Hispa
nic
Asi
an
6 4 7 8
8 1 3 3
2 5 5 5
4 2 4 1
6 6 7
9 re the mean number of times a month a person eats out the same for whites,
blacks, Hispanics and Asians? Suppose that Table 13.26 shows the results of a
study.
Whi
te
Blac
k
Hispa
nic
Asi
an
6 4 7 8
8 1 3 3
2 5 5 5
4 2 4 1
6 6 7
10. s the variance for the amount of money, in dollars, that shoppers spend on
Saturdays at the mall the same as the variance for the amount of money that
shoppers spend on Sundays at the mall? Suppose that the Table 13.34 shows the
results of a study.
Saturd
ay
Sund
ay
Saturd
ay
Sund
ay
75 44 62 137
18 58 0 82
150 61 124 39
94 19 50 127
62 99 31 141
73 60 118 73
89

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