Deck 9: Effect Size and Meta-Analysis

Question 1

What is the definition of effect size?

A) the size of a difference when it is expressed on a standardized scale
B) the size of the difference in raw-score means between groups
C) the size of the standard deviation of results
D) the size of the difference between the hypothesized results and the actual data

Answer 1

the size of a difference when it is expressed on a standardized scale

Question 2

Suppose a researcher conducted an experiment on improving algebra achievement, and the experimental posttest raw-score mean equaled 500.00 (sd = 100.00), and the control group raw-score mean equaled 400.00 (sd = 100.00). What is the value of the effect size for the experiment?

A) 0.0
B) 0.1
C) 1.0
D) 1.1

Answer 2

1.0

Question 3

In this topic, the raw-score differences between the means (5 for Experimenter A and 10 for Experimenter B) were standardized by dividing each of them by what statistic?

A) effect size or d
B) the difference of the means
C) the median of the raw scores
D) the standard deviation

Answer 3

the standard deviation

Question 4

If the value of d for the difference between two means equals 1.00, the experimental group's mean is how many standard-deviation units higher than the control group's mean?

A) 0.1
B) 0.5
C) 1.0
D) 1.4

Question 5

Using Cohen's suggested descriptors, a value for d of 0.20 would be described as what?

A) very small
B) small
C) medium
D) large

Question 6

What is the "effective range" of standard deviation units on both sides of the mean?

A) 1.0
B) 2.0
C) 3.0
D) 4.0

Question 7

According to this topic, what are the two measures of effect size that are very widely reported?

A) Cohen's d and effect-size r
B) Cohen's d and standard deviation
C) effect-size r and standard deviation
D) effect-size r and correlation coefficients

Question 8

Cohen's d is expressed on a standard-deviation scale that typically ranges from what to what?

A) -1.00 to +1.00
B) -2.00 to +2.00
C) -3.00 to +3.00
D) 0.00 to +3.00

Question 9

A value of r should be interpreted by doing what?

A) squaring
B) multiplying by 100
C) squaring then multiplying by 100
D) rounding then multiplying by 100

Question 10

Meta-analysis is used for what?

A) combining the results of previous studies
B) analyzing the results of previous studies
C) inferring from the results of a current study
D) projecting the results of future studies

Question 11

When comparing results between similar experiments, which of the following is NOT a factor identified in this topic as potentially explaining differences?

A) unknown systematic errors
B) known systematic errors
C) random errors of measurement
D) computation errors

Question 12

The experimental group secretly having access to the answer key for the test is an example of what type of error?

A) unknown systematic errors
B) known systematic errors
C) random errors of measurement
D) random sampling error

Question 13

Reliable results may also be said to be valid results.

Question 14

Computing a mean difference across studies that used measurement scales with different possible numbers of score points is meaningless. What is suggested in this topic to overcome this problem?

A) convert to a standardized measurement scale
B) use a measure of effect size such as Cohen's d
C) use regression analysis
D) weight the average value of d

Question 15

What is usually done when the studies to be used in a meta-analysis have different sample sizes?

A) convert to a standardized measurement scale
B) use a measure of effect size such as Cohen's d
C) use regression analysis
D) weight the average value of d

Question 16

Which standardized measure of effect size is used in meta-analytic studies?

A) effect-size r
B) Cohen's d
C) standard deviation
D) both a. and b.

Question 17

Which of the following describes the weakness of meta-analysis known as publication bias?

A) researchers rarely publish results that are not statistically significant
B) researchers tend to use studies published in peer-reviewed journals
C) researchers give more weight to studies published in prestigious journals
D) all of the above

Question 18

Which of the following is a potential weakness of meta-analysis, as described in this topic?

A) use of moderator variables
B) lack of objectivity
C) lack of diversity in sample selection
D) independent confirmation

Question 19

In a report in which separate analyses are conducted for various subgroups, what is the variable on which the studies were divided into subgroups called?

A) group variable
B) moderator variable
C) meta-variable
D) correlation variable