What unit of measurement does Cohen’s d use to express the difference between a control group mean and an experimental mean?

1) You want to compare improvement in depression scores on the PHQ-9 Quick Depression Assessment (on a scale of 0-27 where 0 represents no depression and 27 represents severe depression) between one group of 35 teenagers who participate in a singing class and a second group of 38 teenagers who participate in a boxing class. Mean improvement in depression scores over a 2-month period are:

 	Change in depression score	Standard deviation
Singing Class	   -5.72	  1.43
Boxing Class	   -8.46	  2.19

 

What statistic will show you how much the boxing class reduced the teenagers’ depression scores?

 

1. a) R
2. b) R^2
3. c) r
4. d) r^2
5. e) p
6. f) X^2
7. g) d
8. h) F
9. i) t

 

 

2) Individuals experiencing depression were divided into three groups. Each group was counseled for different amounts of time (1 month, 6 months, or 12 months) to see how they scored on measures of psychological wellbeing.

What is the best test to find differences among the groups?

 	t-test of independent means
 	t-test of dependent means
 	ANOVA
 	Chi-square
 	Pearson r

 

3) You want to learn whether women named Sarah are more likely to have grown up in the Midwest and whether women named Sara are more likely to have grown up in the East.

What is the best test?

 	t-test of independent means
 	t-test of dependent means
 	ANOVA
 	Chi-square
 	Pearson r

 

 

4) You need to find whether different levels of happiness are associated with different levels of income.

What is the best test?

 	t-test of independent means
 	t-test of dependent means
 	ANOVA
 	Chi-square Pearson r
 	 
 	 

5) Which of these values in an ANOVA table is of greatest interest?

 	Mean squares.
 	The value of p.
 	The value of F.

 

 

 

 

 

 

6) If you read,&nbsp;F&nbsp;= 3.50,&nbsp;df&nbsp;= 2, 20,&nbsp;p&nbsp;< .05, what conclusion do you draw?

   a) The means tested differed.
 	b) More than two groups or multiple measurement points were employed in the study.
 	c) The relationship tested is statistically significant.
 	d) All of the above.
 	e) None of the above.

&nbsp;

7) Equating a significant difference with a large difference is a mistake.

True

False

&nbsp;

8) In an experiment with a treatment and control group, what does&nbsp;d&nbsp;= 2 mean?

 	a) The average participant in the experimental group did two standard deviations better on some measure than the average participant in the control group.
 	b) The average participant in the experimental group did two standard deviations worse on some measure than the average participant in the control group.

&nbsp;

9) A large effect size might represent an unimportant result

True or False

&nbsp;

10) To determine whether AIDerall enhances studying, you give the drug to a group of 14 students and engage another 14 students as a control group. Both groups then solve 40 mathematical problems. The lowest score students can receive is zero; the highest is 40. Students who took AIDerall received these scores: 32, 25, 17, 12, 17, 22, 27, 30, 27, 21, 19, 25, 23, 28. Students in the control group received these scores: 33, 21, 14, 20, 36, 11, 32, 12, 15, 18, 19, 22, 14, 13

&nbsp;

For the AIDerall group and rounding every answer to the nearest integer, what are the:

&nbsp;

Mean: [“5”, “8”, “14”, “19”, “20”, “23”, “24”, “25”]

Median: [“5”, “8”, “14”, “19”, “20”, “23”, “24”, “25”, “17”]

Standard Deviation: [“5”, “8”, “14”, “19”, “20”, “23”, “24”, “25”]

&nbsp;

For the control group and rounding every answer to the nearest integer, what are the:

Mean: [“5”, “8”, “14”, “19”, “20”, “23”, “24”, “25”]

Median: [“5”, “8”, “14”, “19”, “20”, “23”, “24”, “25”]

Standard Deviation: [“5”, “8”, “14”, “19”, “20”, “23”, “24”, “25”]

&nbsp;

&nbsp;

What is the&nbsp;d&nbsp;(using for your computations the rounded integers you previously derived):

&nbsp;

[ Select ]

[“.2”, “.25”, “.275”, “.3”, “.35”, “.40”, “.425”, “.461”, “.48”, “”]

&nbsp;

How would you analyze the data from this study?

&nbsp;

[ Select ]

&nbsp;

[“t-test”, “ANOVA”, “Chi-square”, “Pearson”]

&nbsp;

11) ANOVA yields what statistic?

F d r

t  

12) A small, significant difference is not an important finding.

True or False
 	 

13) Which of the following yield(s) a p value?

(select all possible answers)

 	t test
 	Cohen’s d
 	chi-square
 	ANOVA
 	Pearson’s r

&nbsp;

14) Insignificant differences are not useful. True or false?

&nbsp;

15) What unit of measurement does Cohen’s d use to express the difference between a control group mean and an experimental mean?

&nbsp;

16) All following questions are about Table 1.

Table 1. Outcomes of Cognitive-Behavior Therapy (CBT), Motivational Interviewing (MI), or No Therapy (Control)

 

 

CBT (n = 124)

 

MI (n = 115)

 

Control (n = 112)

 

 

Cohens’ d

 

 

M or %

SD or (SE)

 

M or %

SD or (SE)

 

M or %

SD or (SE)

 

X2, t, or F

CBT – Control

MI – Control

 

Age

45.5

5.1

 

44.9

4.7

 

44.5

4.9

 

1.67*

 

 

 

Female

41%

 

 

44%

 

 

42%

 

 

0.88

 

 

 

Depressiona

18.9e

12.4

 

24.6

11.9

 

23.2

15.9

 

   2.33**

0.27

 

 

Anxietyb

33.2e

8.6

 

30.3f

7.1

 

35.7

6.8

 

   2.04**

0.37

0.79

 

Medicationc

27.5

3.3

 

19.8

2.7

 

 

 

 

   5.16***

 

 

 

Alcohol used

12.6

2.4

 

12.5

2.7

 

12.9e

2.1

 

   3.14**

0.27

0.36

 

Notes. aBeck Depression Inventory (0 – 35); lower scores indicate less depression. bMarquart Anxiety Scale (0 – 100); lower scores indicate less anxiety. cDays of using mood management drugs during CBT or MI (0 – 60). IDays on which one or more alcohol drinks were consumed in last month (0 – 30). Dissimilar subscripts indicate that means differ p < .05.

*p < .10; **p < .05; ***p < .01.

&nbsp;

Did age significantly differ by treatment group?

 	Yes
 	No
 	Cannot determine from the table.

&nbsp;

17) What test was used for comparing these variables?

Age

 	Independent t
 	Dependent t
 	Chi-square
 	Pearson r
 	ANOVA
 	Cannot determine

&nbsp;

18)Female

 	Independent t
 	Dependent t
 	Chi-square
 	Pearson r
 	ANOVA
 	Cannot determine

&nbsp;

19) Depression

 	Independent t
 	Dependent t
 	Chi-square
 	Pearson r
 	ANOVA
 	Cannot determine

&nbsp;

20) Anxiety

 	Independent t
 	Dependent t
 	Chi-square
 	Pearson r
 	ANOVA
 	Cannot determine

&nbsp;

21) Medication

 	Independent t
 	Dependent t
 	Chi-square
 	Pearson r
 	ANOVA
 	Cannot determine

&nbsp;

22) Alcohol use

 	Independent t
 	Dependent t
 	Chi-square
 	Pearson r
 	ANOVA
 	Cannot determine

&nbsp;

23) If you had to decide which treatment worked best, what would be the basis for your conclusion? Mark all that apply.

 	M differences
 	p values
 	d values
 	SDs
 	Number of asterisks
 	Footnotes
 	All of the above
 	Cannot determine