1. You see the following in a journal article: Children's reading abilities improved after their participation in the reading clinic program compared to before the program, t (55) = 1.93, p < .05. one tailed a) How many children participated in the study?b) What was the limit for the probability of making a Type I error?c) Would this have been a significant result if we did an alpha = .05 (2 tailed) test? d)What is the effect size (hint: compare the formula for t and d', they have a lot in common)

2. You wish to examine the effect of hours of sunlight on vitamin D absorption.You select a group of students who attend Brock's Florida campus and record the amount of vitamin D in their system during December.You compare them to a group of Brock students at the St Catharines campus during December.What is the DV? What is the IV? What type of measurement scale is the DV?What would be the appropriate hypothesis test (use the chart at the end of chapter 18 by answering the questions in the Diamonds).

3. You have a hypothesis that drivers today are less likely to have an automobile accident because people are driving less because of the pandemic.You find data from a national study 20 years ago indicating that there were 6.88 accidents (SD = 1.75) per 100,000 hours driven on average.You examine data from 10 cities from across Canada and find that the rate among them is just 4.75? What is the appropriate hypothesis test (tell us why by answering the questions in the diamonds from the flow chart at the end of chapter 18)?Would you use 1-tail or 2-tail test? WHY?

4. You are interested in implementing a workshop to help students deal with exam anxiety, but this can be costly as a registered mental health professional is required to lead the workshop. Thus, you decide to test the effectiveness of the intervention on a smaller number of students. You ask nine students to write an anxiety questionnaire (scored from 0-100; higher scores indicate greater anxiety) before and after the workshop. The data are shown below.

a) Was this intervention helpful? Would you implement it on a larger scale?

b) What is the effect size?

c) Are you more concerned about Type I or Type II error?

Before

After

D

D²

70

55

15

225

60

55

5

25

20

22

-2

4

67

40

27

729

88

80

8

64

94

79

15

225

38

42

-4

16

50

42

8

64

82

73

9

81

X

569

488

81

1433

Variance

582.9444

396.4444

88

52521.9444

5. Dr. Caitlin Mahy studies the development of children's memory here at Brock. She wants to know whether young children's memory performance differs when they are given a reminder compared to no reminder. Below are data from 24 children either in a no reminder condition or a reminder condition. Their scores indicate their memory performance (Number of tasks remembered from 0 to 10). What would you conclude? What is the effect size?How can you increase the power of this design?

No Reminder

Reminder

D

D²

1

8

7

1

1

2

6

9

-3

9

3

1

4

-3

9

4

4

7

-3

9

5

3

6

-3

9

6

4

6

-2

4

7

5

6

-1

1

8

2

9

-7

49

9

7

6

1

1

10

10

9

1

1

11

2

7

-5

25

12

2

4

-2

4

X

54

80

-26

122

X

328

566

122

3386

St Dev

2.7798

1.7233

2.4433

13.9664