groups of subjects use a between-groups design. For example, a researcher who
is studying condom use among adolescents may wish to know the practices of
high school juniors and seniors as well as college freshmen and sophomores.
The researcher could make comparisons among these four groups about the
frequency of condom use.
Although comparisons among diverse subjects are important, there may be
other situations when researchers are more interested in making comparisons
within the same subject. For example, a researcher is interested in the effect
of music therapy on patients’ levels of pain. Using a within-groups design, the
researcher would measure the subjects’ levels of pain before the intervention,
conduct the intervention, and then measure pain levels after the intervention.
By comparing the subjects’ pain scores before and after the intervention, the
researcher is able to determine the effectiveness of music therapy as a pain
relief measure.KEY TERMS
between-groups
design: Study
design where two
groups of subjects
can be compared
within-groups
design:
Comparisons are
made about the
same subjects at
two or more points
in time or on two or
more measures- When designing a study, which of the following should the researcher consider? (Select
all that apply.)
a. Research question
b. Review of the literature
c. Theoretical framework
d. Study purpose - Which of the following is not a purpose of nonexperimental designs?
a. Describe phenomenon
b. Explain relationships
c. Predict relationships
d. Examine causality - What is the researcher’s ability to manipulate or regulate extraneous variables known as?
a. Control
b. Manipulation
c. Bias
d. Probability - When a researcher assigns subjects to groups by tossing a coin, the researcher is using
which technique?
a. Random selection
b. Random assignment
c. Bias
d. Within-groups design
TEST YOUR KNOWLEDGE 6-1
How did you do? 1. a, b, c, d; 2. d; 3. a; 4. b154 CHAPTER 6 Key Principles of Quantitative Designs