Topic 37
1. What is the purpose of an experiment?
The purpose of an experiment is to explore cause-and-effect relationships.
2. How can researchers ensure that there are no biases in the assignment of
participants to groups in an experiment?
By assigning participants at random to groups, researchers are assured that
there are no biases in the assignment.
3. In a diagram for an experimental design, the symbol “O” stands for what?
The symbol “O” stands for observation or measurement.
4. In a diagram for an experimental design, the symbol “X” stands for what?
The symbol “X” stands for experimental group.
5. What is the name of the potential problem caused by the pretest in the
pretest-posttest randomized control group design?
The name of the potential problem caused by the pretest in pretest-posttest
randomized control group design is called pretest sensitization.
6. What is the name of the true experimental design that has no pretests?
A true experimental design that has no pretests is called posttest-only
randomized control group design.
7. What is the potential drawback to the Solomon randomized four-group
design?
The only potential drawback is that a researcher must begin with a
reasonably large pool of participants so that when they are divided into four
groups, each of the groups will have sufficient number to yield reliable
results.
8. True experimental designs are easy to spot because they are all characterized
by what?
True experimental designs are easy to spot because they are all characterized
by random assignment to treatments.
Topic 38
1. What is the name of the threat that indicates that taking a pretest may affect
performance on a posttest?
The name of the threat that indicates that taking a pretest may affect
performance on a posttest is called history.
2. Suppose an experimental group is being taught letters of the alphabet as a
treatment. At about the same time, the students are watching an educational
program on television, from which they learn the names of the letters. What
is the name of the threat that this problem illustrates?
This scenario would describe maturation participants matured and became
older, wiser, or smarter.
3. If observers are more tired and less astute when making posttest
observations than when making pretests observations, what is the threat is
operating?
Instrumentation refers to possible changes in the instrument or
measurement procedure.
4. What is the name of the threat posed by nonrandom assignment of
participants to experimental and control groups?
Selection is a threat to internal validity if researchers do no assign groups
randomly.
5. If infants naturally improve in visual acuity and thus perform better at the
end of an experiment than at the beginning, what threat is operating?
Testing is the threat operating.
6. Under what circumstance will statistical regression operate?
Statistical regression is another threat that occurs only if participants are
selected on the basis of their extreme scores.
7. How can researchers overcome all the threats to internal validity?
All threats to internal validity can be overcome by using a true experimental
design.
Topic 39
1. Which type of validity deals with the question of whether a researcher can
generalize with confidence to a larger population in a natural setting?
External validity asks the question of whether a research can generalize with
confidence to a larger population in a natural setting.
2. Which type of validity deals with whether the treatment is directly
responsible for any changes observed in the experimental setting?
Internal validity deals with whether the treatment is directly responsible for
any changes observed in the experimental setting.
3. What is the name of the threat that warns researchers to be careful in
generalizing the results to a population when an experiment is conducted on
a nonrandom sample?
Selection bias warns researchers to be careful in generalizing the results to a
population when an experiment is conducted a nonrandom sample.
4. Suppose a random sample of workers in a factory is exposed to five different
reward systems, with each system being used for one month. What is the
name of the threat that reminds researchers that the results may not
generalize to the population of workers if the population is to be exposed to
only the last reward system tried in the experiment?
Multiple-treatment interference is a threat that occurs when a group of
participants is given more than one treatment.
5. Suppose an experimental classroom has research observers present at all
times. What is the name of the threat that reminds researchers that the
results may not generalize to other classrooms without observers?
Reactive effects of experimental arrangements remind researchers that the
results may not generalize to other classrooms without observers.
6. If a pretest causes a change in participants’ sensitivity to a treatment, what
threat is operating?
Reactive effect of testing is a threat that refers to the possibility that the
pretest might influence how the participants respond to the experimental
treatment.
Topic 40
1. Are pre-experimental designs valuable for identifying cause-and-effect
relationships?
No, pre-experimental designs are of very limited value for investigating
cause-and-effect relationships.
2. Suppose a researcher administered a new program to all students in a school.
At the end of the school year, the researcher administered a standardized
test to the students in the school as well as to students in another school who
were serving as a control group. Is the comparison of the average scores for
the two groups of students useful for determining the effects of the program?
No, because the groups were not given a pretest so a researcher does not
have a basis for knowing whether the two groups were similar at the
beginning of the experiment.
3. What is the name of the pre-experimental design used in Question 2?
Static-group comparison design
4. If a researcher gives a pretest on knowledge of child abuse to a group of
social workers, then gives them a series of seminars on child abuse followed
by a posttest, what is the name of the pre-experimental design the researcher
used?
One-group pretest-posttest design
5. Is the design used in Question 4 useful for determining cause-and effect
relationships?
Yes, because the group was given a pretests, a treatment, and a posttest.
Researchers can compare the data to see how the treatment affected the tests
scores.
Topic 41
1. What is the name of the design diagrammed immediately below?
Nonequivalent control group design
2. In the design show in Question 1, what indicates that the participants were
not assigned at random to the groups?
A dashed line in the design indicates that the participants were not assigned
at random to the groups.
3. If a researcher uses matching to form the two groups in the design in
Question 1, would the resulting experiment be superior to a true
experiment?
No, assigning participants at random to the two conditions would be vastly
superior.
4. What is a major advantage of the equivalent time-samples design?
Researchers know that the experimental participants and control
participants are identical in their genetic characteristics, income level,
attitudes, and beliefs.
5. What is a major disadvantage of the equivalent time-samples design?
A major disadvantage of this design is the strong possibility of multipletreatment interference.
6. In psychology, what is an ABAB design?
ABAB design is a single-group design in which treatments are alternated,
where A and B indicated alternating treatments.
Topic 42
1. A confound is a source of confusion regarding what?
The explanation for a given difference
2. What is the name of the effect that refers to the possibility that the control
group might become aware of its “inferior” status and respond by trying to
outperform the experimental group?
John Henry effect
3. What is the formal name of what is characterized as the “attention effect” in
this topic?
Hawthorne effect
4. In addition to an experimental and traditional control group (with no
treatment), what other group can be used to control for the Hawthorne
effect?
A control group that receives attention
5. The term “placebo effect” refers to what tendency?
Placebo effect refers to the tendency of individuals to improve simply
because they know they are being treated.
6. In what type of experiment do neither the participants nor individuals
dispensing the drug know which is the active drug and which is the placebo?
In a double blind experiment, neither the participants nor the individual
dispensing the drug know which is the active drug and which is the placebo.
7. A “demand characteristic” is a cue that lets participants know what?
A “demand characteristic” is a cue that lets participants know the expected
outcome of an experiment.