PSY550 Final Exam: Research Methods
Instructions: This is an open-book and open-notes exam. You have 2 hours to complete the exam.
The test is worth 100 points; each item is worth 10 points.
1. Chuck Wagon is very exc
...
PSY550 Final Exam: Research Methods
Instructions: This is an open-book and open-notes exam. You have 2 hours to complete the exam.
The test is worth 100 points; each item is worth 10 points.
1. Chuck Wagon is very excited about the within-subjects approach. “Now I’ll never need
to run large numbers of subjects again,” he says. However, Chuck has forgotten that
within-subjects designs may be a) useless, b) impossible, c) confounded by order effects, or
d) impractical when excessive subject time spent in an experiment makes data inaccurate.
Give an example of each of these four objections.
Answer:
a). useless- a within-subjects design would be useless if we were studying the effectiveness of
two learning programs (reading for instance). If a student completed one program to learn how
to read, it would be useless for them to complete the other program as they already gained the
skills in the first program, and thus could not truly test the effectiveness of the second program.
b). impossible- a within-subjects design is impossible when you fail to find a sample that is
representative of the population. For instance, if gender is a variable (independent variable), a
participant cannot be both male and female, and thus it is impossible to measure within-subjects.
c). confounded by order effects- If you were to provide tips or suggestions on how to play an
instrument to see if they improve over prior to the tips, but there is no way to know if
improvement in the skill came from the tips provided or from practicing the instrument. The
order of the conditions cannot be changed as the participants cannot unlearn the tips that were
provided to them.
d). impractical when excessive subject time spent in an experiment makes data inaccurate- If too
many conditions are presented to participants, or conditions are presented for excessive lengths
of time, participants are likely to become fatigued or even drop out of the study. If a participant
becomes fatigued, they are less likely to be able to pay attention to the conditions and thus, likely
to not provide accurate information to the research.
2. Explain the pros and cons of longitudinal, cross-sectional, and sequential designs.
Answer:
-Longitudinal design is defined in our text as a developmental research design that is utilized to
study the changes of its participants across a life span. This is done by observing the same set of
participants and different points in time, and measuring the same dependent variable at each
point in time (Privitera, 2017). A pro to this is the ability to learn a developmental course
through continuity and it eliminates cohort. A con to this design si that these are usually costly
designs, they take a long time, participants can drop out or pass. Additionally, long term research
increases the chances of unpredictable outcomes.
-Cross-sectional design is defined in our text as a developmental research design in which
participants are grouped by their age and participant characteristics are measured in each age
group (Privitera, 2017). Pros of this design are the low cost and speed of study, the ability to
prove or disprove assumptions and multiple variables are viewed at the time of the data snapshot.
Cons of this design study are that they cannot be used to analyze behaviors, they are useless for
determining cause and effect and they cannot show any developmental progress.
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-Sequential design is defined in our text as a developmental research design that combines
longitudinal and cross-sectional techniques by observing different cohorts of participants over
time at overlapping times (Privitera, 2017). A pro of this design study is the ability to compare
cohorts as it is a hybrid design and it is not very costly. A con is the complications that come
with this type of design. Determining the cause behind a trend is difficult to ascertain in this
design.
3. After watching nursery-school children, Ken Garoo wants to test the hypothesis that
some toys are more fun to play with than others. He decides to compare “fun” toys (blocks)
with “unfun” toys (stuffed animals). He also wishes to see if there is a sex difference, as
well, so sex is added as an independent variable. A) What kind of design is needed? B)
Diagram it out. C) Assuming 20 subjects are needed per cell, how many subjects are needed
for this study?
Answer:
(a) Randomized block design
(b)
Male Female Total
Fun toys
Unfun toys
Total
4. Define the term quasi-experiment and discuss the pros and cons of this research method.
Answer:
Quasi-experimental research is defined as the use of methods and procedures to make
observations in a study that is structured similar to an experiment (Privitera, 2017). However,
the conditions and experiences of the participants lack some control because the study lacks
random assignment, includes a preexisting factor and does not include a comparison or control
group. Pros of this design are monitors independent variables to ensure that unwanted variables
are eliminated and thus this design can produce the best results. The cons to this can be practical
and ethical issues and lacks comparison/control.
5. Bill Board is “lording” his SAT score over his friend, Rhoda Dendron, who took the
ACT. “You only got a 25 in math,” he chortled, “while I got a 300 in math.” Given that the
SAT has a μ of 500 and a σ of 100, and the ACT has a μ of 20 and a σ of 5, what is wrong
with Bill’s logic (give the answer in both z scores and percentile ranks).
Answer:
z=
x−μ
σ
Bill: ¿
300−500
100 = -2 300
800 = 37.5%
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Rhoda = 25−20
5
= 1
25
36 = 69%
Bill’s logic is faulty because he is comparing tests with different means, different scoring
components.
6. For each of the following examples, explain whether the researcher has made a correct
decision or has made a Type 1 or Type 2 error. Explain why.
a) Dr. G rejects the null hypothesis although the independent variable had no effect.
b) Dr. R rejects the null hypothesis when it is false.
c) Although the independent variable had an effect, Dr. E does not reject the null
hypothesis
Answer:
(a) Type 1, if the independent variable has no effect, it should not be rejected (type 1 rejects the
hypothesis when it is in fact true)
(b) Correct
(c) Type 2, if the independent variable has an effect it should be rejected (type 2 does not reject
the null hypothesis when the alternative is true)
7. A researcher has studied subjects’ ability to learn to translate words into Morse code. He
has experimented with two treatment conditions: in one condition, the subjects are given
massed practice; they spend 8 full hours on the task. In the other condition, subjects are
given distributed practice; they also spend 8 hours, but their practice is spread over four
days, practicing 2 hours at a time. After the practice, all subjects are given a test message to
encode; the dependent variable is the number of errors made. The researcher has matched
the subjects on intelligence. The results are in the following table. Decide which statistical
test would be appropriate, carry out the test, and evaluate the outcome. Assume a
significance level of .05 and that the direction of the outcome has not been predicted.
Massed Practice Distributed Practice
S1 6 S1 5
S2 4 S2 3
S3 3 S3 2
S4 5 S4 2
S5 2 S5 3
Answer:
Subject Massed Distributed d=Massed-distributed
1 6 5 1
2 4 3 1
3 3 2 1
4 5 2 3
5 2 3 -1
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H0=μd=0
Ha=μd≠ 0
The mean and standard deviation of d are:
d´ =
∑d
n
=
1+1+1+3−1
5
=1
sd=√
∑(d−d´)
2
n−1
df =n−1=5−1=4
Given = 0.05, we use a t table for a two tailed test; thus reject the null hypothesis if
|t|>2.776
The test statistic is:
t=
´d
sd
√n
=
1
1.41
√5
=1.581
Since t is less than 2.776, fail to reject null hypothesis. There is no significant difference.
8. Explain the value of reversal designs (ABA designs) in single-case research.
Answer:
ABA designs, also known as reversal designs, is defined in our text as, a single-case
experimental design in which a single participant is observed before (A), during (B), and after
(A) a treatment or manipulation (Privitera, 2017). This is to say that a participant is selected and
documented as is, a treatment is introduced and documented and then the treatment is removed
and documented to determine how effective the treatment is. This is valuable in research as a
baseline is created. This method can allow a researcher to confirm a treatment effect by showing
that behavior changes systematically with conditions of no treatment (baseline) and treatment.
9. Explain how a one-way analysis of variance works. How do you use between- and withingroup variability?
Answer:
One-way analysis of variance is applied when we need to check for the equality of variance of
more than two (not equal to) set of values, the null hypothesis being that there is no difference
between the means of all the set of values against the alternative that there is a difference in
means of at least two set of values. This test is used when different participants are observed at
each level of a factor and the variance of a given population is unknown.
The between- group variability denotes the difference between the values of two sets, whereas
the within-group variability means the difference between the values of the same set of values.
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10. Describe a two-matched groups design. How is the matching done?
Answer:
A matched pairs design is a within-subjects research design in which participants are matched,
either experimentally or naturally, based on preex
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