Design Chapter 3 Next time: Continue Design

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Design (Chapter 3)Next time Continue Design
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Dear Psychology Research Faculty   It is with
great excitement that I write this letter to
announce the application deadline for the 2009
UCLA Psychology Undergraduate Research Conference
(PURC). Each year the Department of Psychology
at UCLA hosts its annual undergraduate research
conference, which features undergraduate projects
showcased in poster and paper talk sessions. In
2008 this conference featured 98
projects presented by 150 students from 24
different campuses.  This year, the event will
take place on Friday, May 8th. We are looking
for a diverse representation of campuses and we
would like to see more applicants from the
University of Florida. We are looking for high
quality abstracts written by undergraduate
researchers in your department. Please encourage
your independent researchers and students who are
assisting you with your research efforts to
apply. We realize that this conference may not be
a convenient location for students attending
schools outside of the Los Angeles area. However,
we do know that many studen ts at your
institution are from Southern California and may
want to present at a conference close to home.  
To apply, students must submit the application,
an APA abstract, and the application fees by
Friday, March 6th, 2009. The application and
application directions are available online at
http//purc.bol.ucla.edu/09Application.pdf.  
Sarah Bejarano PURC Coordinator, Department of
Psychology, UCLA bejarano_at_psych.ucla.edu    
rano_at_psych.ucla.edu    
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I am writing to share with you a wonderful
summer research opportunity at the University of
Maryland, College Park intended for undergraduate
students (see attached announcement). This
program is geared at rising juniors and seniors
who are interested in pursuing a doctorate in the
social, behavioral and economic sciences
immediately following the completion of the
Bachelors degree. All students are eligible
however, we highly encourage those from
under-represented populations to apply (i.e.
African Americans, Hispanics, American Indians,
Alaska Natives, Native Hawaiians, or other
Pacific Islanders). We expect 10-12 scholars to
participate in the upcoming eight-week experience
(from June 1- July 24, 2009). Events and
activities will include lab and research
experiences, didactic science lectures, and
opportunities for professional development,
mentoring, and networking. Accepted students will
be provided round-trip airfare, meals, room and
board and a 2,700 stipend. The application
deadline is February 13, 2009. We would greatly
appreciate your help in disseminating this
announcement to your students and colleagues.
Please refer them to our program website
http//www.bsos.umd.edu/diversity/summer-research-
initiative.aspx or email us at sri_at_bsos.umd.edu
Thank you. David Garcia SRI Coordinator Summer
Research Initiative Office of the Dean College of
Behavioral and Social Sciences University of
Maryland - College Park 2141 Tydings Hall College
Park, MD 20742 (T) 301-405-8761 (F) 301-314-9086
(E) sri_at_bsos.umd.edu
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Design (Chapter 3)Next time Continue Design
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Cross-SectionalLongitudinal
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Cross-sectional design Design for age
comparisons in which different participants are
studied at the different ages, all at the same
time
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Time of Measurement 1990 2000
2010Year 1930 60 70 80 of
1940 50 60 70 Birth 1950 40
50 60
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Longitudinal design Design for age comparisons
in which the same participants are studied at
different ages over time
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Time of Measurement 1990 2000
2010Year 1930 60 70 80 of
1940 50 60 70 Birth 1950 40
50 60
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Possible problems with cross-sectional designs
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Possible problems with cross-sectional designs

• Selection bias (p. 32)

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Possible problems with cross-sectional designs

• Selection bias (p. 32)
• Selective drop-out (p. 33)

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Time of Measurement 1990 2000
2010Year 1930 60 70 80 of
1940 50 60 70 Birth 1950 40
50 60
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Possible problems with cross-sectional designs

• Selection bias (p. 32)
• Selective drop-out (p. 33)
• Measurement equivalence (p. 33)
• Confound of age and cohort
• Cant study individual stability or change

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Time of Measurement 1990 2000
2010Year 1930 60 70 80 of
1940 50 60 70 Birth 1950 40
50 60
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Possible problems with longitudinal designs

• Practical difficulties
• Selective drop-out
• Limitation to a single cohort
• Effects of repeated testing
• Measurement equivalence
• Confound of age and time of measurement

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Time-lag design Design in which participants of
the same age but different cohorts are studied at
different times
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Time of Measurement 1990 2000
2010Year 1930 60 70 80 of
1940 50 60 70 Birth 1950 40
50 60
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Sequential design Design in which longitudinal,
cross-sectional, and time-lag components are
combined in an attempt to distinguish effects of
age, cohort, and time of measurement
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Time of Measurement 1990 2000
2010Year 1930 60 70 80 of
1940 50 60 70 Birth 1950 40
50 60
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Between-Subject vs. Within-Subject Designs
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Between-Subject vs. Within-Subject Designs

• Convenience

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Between-Subject vs. Within-Subject Designs

• Convenience
• Statistical tests

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Between-Subject vs. Within-Subject Designs

• Convenience
• Statistical tests
• Possible selection bias

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Between-Subject vs. Within-Subject Designs

• Convenience
• Statistical tests
• Possible selection bias
• Effects of repeated testing

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Order EffectCarry-Over Effect
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Order Effect First SecondNumber
5 7Quantity 5 7
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Carry-Over Effect First SecondNumber
7 5Quantity 5 7
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Between-Subject vs. Within-Subject Designs

• Convenience
• Statistical tests
• Possible selection bias
• Effects of repeated testing
• Focus on within-subject patterning

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Between-Subject vs. Within-Subject Designs

• Convenience
• Statistical tests
• Possible selection bias
• Effects of repeated testing
• Focus on within-subject patterning
• Procedures that produce lasting change