# Statistical Methods I – Psych 2021 3.0 C – Rumor has it, going to class and reading the textbook will

August 30, 2017

Question
Assignment 2

Statistical Methods I – Psych 2021 3.0 C

Due: At the final exam on December 18, 2015

(Make sure to show all your work, including your formulas, for all calculations)

Total marks: 31

1. Rumor has it, going to class and reading the textbook will improve your chances of doing well (i.e., better than average) in statâ€™s class. You notice that there are 4 students that always go to class and review the textbook everyday. To determine if the rumors are true, you ask those 4 students their marks on the quiz and find that their scores are:

60

60

61

67

Based on these scores and the knowledge that the exam scores are normally distributed (?=50, ?=10), what can you conclude about going to every class and reviewing the textbook everyday on marks on the quiz? Do you reject or fail to reject the null hypothesis? What is the effect size? Assuming ?=0.05, state your hypotheses for a one-tailed test, the critical test statistic, your conclusion, and show all your work.(8 marks)

Car insurance companies assume that the longer a person has been driving, the less likely they will be in an accident, and therefore charge new drivers higher insurance premiums than experienced drivers. To determine whether driving experience is related to the number of car accidents, you survey a random sample of 12 Torontonians and ask them about the number of years they have been driving, and the number of car accidents they have been involved in during the past year. The data are presented below:
Driver

# of years driving (X)

# of car accidents (Y)

A

4.5

3

B

2.5

5

C

1.5

3

D

3

3

E

1.5

6

F

5

2

G

5

0

H

2

4

I

3

1

J

4

2

K

1

5

L

3

2

a. Determine whether the assumptions of car insurance companies are valid. Assuming ?=0.05, include the hypotheses for a one-tailed test, critical test statistic, conclusion, and all formulas and calculations.(8 marks)

b. Is it appropriate to conclude that lack of driving experience causes accidents? Why or why not?(2 marks)

3. A researcher is interested in how stereotypes can affect perception among people in the stereotyped group. In this case, the researcher wants to examine whether there are any perceptual differences between young and old people after they are primed with old-age stereotypes (i.e., stereotypes are subconsciously triggered). The researcher obtains 50 university students and 50 seniors and primes them with old-age stereotypes. They are then given the following ambiguous picture, and asked whether they see an old woman or a young woman. It is believed that if the person is old, thinking about old-age stereotypes will result in seeing the old woman in the picture before seeing the young woman. Conversely, if the person is young, thinking about old-age stereotypes will make no difference. The data are presented below:

Young Woman

Old Woman

Young Participants

23

27

50

Old Participants

12

38

50

35

65

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a. Calculate the expected number of participants for each condition. Determine whether there are any significant differences in the proportion of young and old participants who see the old woman first. Assuming ?=0.05, include the hypotheses, the critical test statistic, conclusion, and all formulas and calculations.(8 marks)

b. Determine the strength of this relationship. Is this a large, medium, or small effect?(2 marks)

Attachments
assignment2.doc (58.5 KB)

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