Download - WEBPSY330 QuasiExperimental Group
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Quasi & Non-Experimental Designs
Quasi-Experimental designs: Not quite true experiments
because the different groups/conditions are not
created by __________________. Groups or
conditions are defined by _____________ variable ora ______ variable.
Non-Experimental designs do not allow you to rule out
many threats to _______________.
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Quasi & Non-Experimental Designs
Those using ____ group, compare behavior across _____:
Time-series designs (quasi-experimental)
One group pretest-posttest (non-experimental)
Longitudinal design (non-experimental
Those using multiple, ____________ groups:
1. Pretest-posttest nonequivalent control group design
(quasi-experimental)
2. Posttest-only control group design (Static-group design)
(non-experimental)
3. Differential (Causal-comparative) design (non-
experimental)
4. Cross-sectional design (non-experimental)
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QUASI-
EXPERIMENTAL
NON-EXPERIMENTAL
Time-series design
(One group)
Differential/Causal comparativedesign
(Multiple groups)
Pretest-posttest non-equivalent
control-group design
(Multiple groups)
Developmental: Cross Sectional
design
(Multiple groups)
Developmental: Longitudinal design
(One group)
One-group pretest-posttest design
(One group)
Posttest-only nonequivalent group
(Static) design
(Multiple groups)
Summary of Quasi & Non-experimental designs
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When would you use a quasi-
experimental design?
When you want to investigate a relationship but cannot
create ________ assign groups
It is not _________ to create randomly assigned groups
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Pretest-Posttest Non-Equivalent Control-Group
Design
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Definition: A quasi-experimental design in which behavior
in two _______________groups is measured pre and
post-IV
No random __________ and ___________
Because you measure behavior before treatment you can
evaluate group equivalence - it reduces the threat of
_______________
e.g., Effects of Flexible vs. fixed work hours onproductivity in two factories
e.g., Effects of Home-based vs. School-based
treatment on problem behavior
Pretest-Posttest Nonequivalent Control-
Group Design
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Posttest Only (Static) Group Design
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No random selection and assignment
2 __________________, e.g., children in 2 clinics
Groups should be ______
Susceptible to internal validity threats, e.g., assignment
bias (selection threat) - group assignment is _______
Example: effects of peer tutoring in two classrooms
Posttest Only (Static) Group Design
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____________Design
Intact Group of
Participants
Measurement
of DV
Measurement
of DV
Measurement
of DV
Measurement
of DV
Measurement
of DV
Experimental
Condition
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Time-Series Design
0
5
10
15
20
25
30
35
40
45
SmokingFrequency
Before Campaign After Campaign
0
5
10
15
20
25
30
35
40
45
SmokingFrequency
Intervention
0
5
10
15
20
25
30
35
40
45
Smok
ingFrequency
Intervention
0
5
10
15
20
25
30
35
40
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Smok
ingFrequency
Intervention
Example: Effects of anti-smoking campaign on smoking frequency
No ______ group
hard to tell ifcampaign was effective
Time Series
Effect was just partof periodic ____________
Time Series Effect was just part
of downward ________
Time Series Effect occurs only
after ____________
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Developmental Research Designs
study age-related changes in behavior
Longitudinal design Measuring a variable in individuals over an
___________________
Like a time-series design with no
_______________ Can determine how an individual _________
No cohort effects
Very _____________, expensive
Problems with _____, ________
Group at
Time 1
(e.g., 10 yrs)
Group at
Time 1
(e.g., 20 yrs)
Group at
Time 1
(e.g., 40 yrs)
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One-Group Pretest-Posttest
Design
1 naturally occurring group
Pretest and postest
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One Group Pretest-Posttest Design
Observation made in ____ group before and after
treatment
No attempt is made to control for many threats to
________________