Problem Set 7

1.In a study of the effect of anxiety on the need for affiliation, participants were told either that they would either be giving a speech to a large audience of peers (high anxiety) or that they would be speaking to one experimenter (low anxiety).Subjects were then given a choice between waiting alone before speaking or waiting in the company of others.Below are the number of participants who chose to wait alone or with others in the high and low anxiety conditions.Test the null hypothesis that anxiety had no effect on whether people chose to wait alone or with others. (34 points)

High anxietyLow anxiety

Alone1421

With others2010

Research Problem

Statistical Hypotheses

Decision Rule

Calculations

Decision

Interpretation

2. A purple skittles lover is interested in knowing whether skittle colors are equally distributed in each bag. They open up a bag of skittles and count each color. Their data are below. Test the null hypothesis that the probability of getting any color is equal. (34 points)

RedOrangeYellowGreen Purple

8712149

Research Problem

Statistical Hypotheses

Decision Rule

Calculations

Decision

Interpretation

For each of the following questions, please specify what statistical test should be used. The correct answer can be any test that we covered this semester from correlation through chi square. (4 points each)

3.In a test of the decay theory of memory, participants memorized a list of nonsense syllables and were tested for recall after one hour and then four hours.What statistical test should be used to test the null hypothesis that delay had no effect on their recall scores?

4. Researchers are interested in whether the way instructions are delivered to jurors affects their decision making. They have two groups. In one group the jurors are verbally given instructions from the judge. In the second group the jury is given written instructions to read. What test would the researchers use to test the null hypothesis that how the instructions are given does not affect the juryâ€™s decision making process?

5.A teacher thinks that she has an especially gifted class. She wants to compare their standardized test scores to those for the entire population of 4

th

graders. She knows that district wide the average exam score was a 430 with a standard deviation of 12. Her class of 18 students scored a 495. What test would you use to test the null hypothesis that her class did not do score higher than the rest of the district?

6. An experimenter is interested in testing whether listening to music improves learning how to solve complex equations. She has a control group complete a learning task without music and then an experimental group that listens to current popular music while completing the same task. What test would you use to test the null hypothesis that music does not have an effect on learning?

7. A professor believes there is a relationship between attendance and test scores. What test would she use to test the null hypothesis that there is no link between attendance and performance on a test?

8. Administration at a university believe that students who live on campus during the semester have higher levels of satisfaction with their experience at the university than students living in different off campus options. They sample 20 students who live on campus, 20 who live with roommates in off campus housing, and 20 who live at home with their families while attending classes, and then measure their satisfaction with their experience as students at the university. What test would the researchers use to test their hypothesis about student satisfaction?

9.The director of a juvenile drug rehabilitation center wants to see how their relapse rates compare to the state average. She knows the state average, but does not know the standard deviation for the stateâ€™s relapse rate. What test would she use to test the null hypothesis that her facility does not differ from the state average?

10. The matching hypothesis states that partners in romantic relationships tend to be well matched for attractiveness. Researchers are interested in seeing if this hypothesis generalizes to same sex couples. The researchers collect pictures of the faces of both partners in 30 same sex relationships, and have a group of trained coders rate how attractive each partner is. What test would the researchers use to test the null hypothesis that there is no difference in the attractiveness of same sex partners?

1

Problem Set 7

1. In a study of the effect of anxiety on the need for affiliation, participants were told either that they would

either be giving a speech to a large audience of peers (high anxiety) or that they would be speaking to one

experimenter (low anxiety). Subjects were then given a choice between waiting alone before speaking or

waiting in the company of others. Below are the number of participants who chose to wait alone or with others

in the high and low anxiety conditions. Test the null hypothesis that anxiety had no effect on whether people

chose to wait alone or with others. (34 points)

Alone

With others

High anxiety

14

20

a. Research Problem

b. Statistical Hypotheses

c. Decision Rule

d. Calculations

e. Decision

f.

Interpretation

Low anxiety

21

10

2

2. A purple skittles lover is interested in knowing whether skittle colors are equally distributed in each bag. They

open up a bag of skittles and count each color. Their data are below. Test the null hypothesis that the probability

of getting any color is equal. (34 points)

Red

8

Orange

7

a. Research Problem

b. Statistical Hypotheses

c. Decision Rule

d. Calculations

e. Decision

f.

Interpretation

Yellow

12

Green

14

Purple

9

3

For each of the following questions, please specify what statistical test should be used. The correct answer can

be any test that we covered this semester from correlation through chi square. (4 points each)

3. In a test of the decay theory of memory, participants memorized a list of nonsense syllables and were tested for

recall after one hour and then four hours. What statistical test should be used to test the null hypothesis that delay had

no effect on their recall scores?

4. Researchers are interested in whether the way instructions are delivered to jurors affects their decision making. They

have two groups. In one group the jurors are verbally given instructions from the judge. In the second group the jury is

given written instructions to read. What test would the researchers use to test the null hypothesis that how the

instructions are given does not affect the juryâ€™s decision making process?

5. A teacher thinks that she has an especially gifted class. She wants to compare their standardized test scores to those

for the entire population of 4th graders. She knows that district wide the average exam score was a 430 with a standard

deviation of 12. Her class of 18 students scored a 495. What test would you use to test the null hypothesis that her class

did not do score higher than the rest of the district?

6. An experimenter is interested in testing whether listening to music improves learning how to solve complex

equations. She has a control group complete a learning task without music and then an experimental group that listens

to current popular music while completing the same task. What test would you use to test the null hypothesis that music

does not have an effect on learning?

7. A professor believes there is a relationship between attendance and test scores. What test would she use to test the

null hypothesis that there is no link between attendance and performance on a test?

8. Administration at a university believe that students who live on campus during the semester have higher levels of

satisfaction with their experience at the university than students living in different off campus options. They sample 20

students who live on campus, 20 who live with roommates in off campus housing, and 20 who live at home with their

families while attending classes, and then measure their satisfaction with their experience as students at the university.

What test would the researchers use to test their hypothesis about student satisfaction?

9. The director of a juvenile drug rehabilitation center wants to see how their relapse rates compare to the state

average. She knows the state average, but does not know the standard deviation for the stateâ€™s relapse rate. What test

would she use to test the null hypothesis that her facility does not differ from the state average?

10. The matching hypothesis states that partners in romantic relationships tend to be well matched for attractiveness.

Researchers are interested in seeing if this hypothesis generalizes to same sex couples. The researchers collect pictures

of the faces of both partners in 30 same sex relationships, and have a group of trained coders rate how attractive each

partner is. What test would the researchers use to test the null hypothesis that there is no difference in the

attractiveness of same sex partners?

Problem Set 6

1. In an experiment designed to determine the effect of mood on perception of pain, subjects

were induced to experience a good mood, a bad mood, or had no mood induction. Participants

were then asked to rate the amount of pain they were currently experiencing. Below is a list of

the pain ratings. Test the null hypothesis that mood has no effect on perception of pain. (35

points)

Negative Mood

Positive Mood

Control Group

10

6

11

12

8

2

2

7

5

1

5

6

4

5

7

Research Problem:

Is the perception of pain related to the experience of bad mood, good mood or no

mood induction?

Statistical Hypotheses:

Null Hypothesis: Mood has no effect on the perception of pain

Âµ1 = Âµ2

Alternative Hypothesis: Mood has a significant effect on the perception of pain

Âµ1 â‰ Âµ2

Decision Rule:

Reject the null hypothesis at the .05 level of significance if t is greater than or equal to

2.306 or less than or equal to -2.306, given 8 degrees of freedom.

Use Jamovi to calculate the F value and post hoc tests if warranted. Copy and paste your

outputs here or upload a separate file with your outputs to the assignment in Blackboard.

Decision:

t = -3.86

Since t < -2.306, Reject the null hypothesis
Interpretation:
1
There is enough evidence to support the claim that mood has a significant effect on the
perception of pain.
2
2. In a study of group productivity, participants worked alone or shared the responsibility
for building widgets with one other, with three others, or with fifteen others. Below, are
the data showing the number of widgets each group produced. Test the null hypothesis
that group size had no effect on productivity. (35 points)
Alone
9
10
12
9
Two-person
group
Four-person
group
8
6
5
6
4
6
3
6
Sixteen-person
group
5
8
3
6
Research Problem:
Does group size affect productivity when building widgets?
Statistical Hypotheses:
Null Hypothesis: Group size has no effect on productivity
Âµ1 = Âµ2
Alternative Hypothesis: Group size has a significant effect on productivity
Âµ1 â‰ Âµ2
Decision Rule:
Reject the null hypothesis at the .05 level of significance if t is greater than or equal to
3.182 or less than or equal to -3.182, given 3 degrees of freedom.
Use Jamovi to calculate the F value and post hoc tests if warranted. Copy and paste your
outputs here or upload a separate file with your outputs to the assignment in Blackboard.
Decision:
t = 3.00
Since t< 3.182, We Fail to Reject Null Hypothesis
Interpretation:
There is no enough evidence to support the claim that group size has a significant
effect on productivity when building widgets.
3
3. Consider the following scores in an experiment involving three conditions;
A
B
C
2
2
2
2
5
5
5
5
8
8
8
8
Without actually computing the sum of squares within, what must its value be?
Why? (12 points)
The sum of squares is 72. As evident from the table, the mean is 5. Values in conditions A and C
deviate from the mean by a value of 3. Squaring the deviation we get 9. There are 8 values that
deviate from the mean. Therefore, the sum of squares would be 9*8 = 72.
4. Insert the missing entries in the summary table for a one-way analysis of variance having three
levels of the independent variable and n = 25. (Each answer is 3 points)
Source
SS
df
MS
F
Between
120
2
60
10.91
Within
121
22
5.5
Total
141
4
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