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, F = 3.50, df = 2, 20, p < .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.

 

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

True

False

 

8) In an experiment with a treatment and control group, what does d = 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.

 

9) A large effect size might represent an unimportant result

True or False

 

10) To determine whether Adderall 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 Adderall 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

 

For the Adderall 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”, “17”]

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

 

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”]

 

 

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

 

[ Select ]

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

 

How would you analyze the data from this study?

 

[ Select ]

 

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

 

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

 

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

 

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

 

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). dDays 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.

 

Did age significantly differ by treatment group?

  Yes
  No
  Cannot determine from the table.

 

17) What test was used for comparing these variables?

Age

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

 

18)Female

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

 

19) Depression

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

 

20) Anxiety

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

 

21) Medication

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

 

22) Alcohol use

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

 

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
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