Choosing Research Designs I

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Choosing Research Designs I

• Experimental and Quasi-Experimental

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Experimental Designs

• Experimental research design The researcher has
  control over the experiment in terms of sample
  selection, treatment, environment, etc.
• Experimental designs are typical in psychology,
  medicine, education, etc.

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Experimental Designs

• Experiments often discuss pre and post test
  observations
• POST-TEST ONLY
• X O 1
• Where
• 0t Observation in time t of experimental group
• X Treatment
• 0c Control group

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Experimental Designs

• PRE-TEST POST-TEST
• O1 X O2
• Note how the above test includes no control
  group. What is a control group and why include
  it?
• PRE-TEST POST-TEST WITH CONTROL GROUP
• O1 X O2
• O1 O2

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Key question of Internal Validity

• When we test a hypothesis and either accept it or
  reject it, how do we know that we made the right
  decision?
• What about alternative explanations that we did
  not account for?
• What should we do to gain confidence?

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Internal Validity

• Are there other causes for what I am observing?
  
• If so, a study will lack internal validity if it
  cannot rule out plausible alternative
  explanations.

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Internal Validity of a Study
Is the relationship causal between...

• What you measured and what you saw?
• Your program and your observations?

Alternative cause
Alternative cause
Research Project
Observations
Program-outcome Relationship
What you do
What you see
Alternative cause
Alternative cause
Observation
In this study
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• DID YOU FIND THAT BORING?THEN HOW ABOUT A JOLT
  OF CUTENESS!

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Experimental Designs

• What do you do if you fear that your simple pre
  and post test single observations are atypical?
• CONTROL WITH MORE OBSERVATION IN THE PRETEST
• O1 O2 O3 X O4
• O1 O2 O3 O4

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Experimental Designs

• Of course, we could also experiment to see if
  removing a factor has an effect instead of adding
  a treatment factor
• PRE-TEST POST-TEST REMOVING THE TREATMENT
• _
• O1 X O2 X O3 X 04

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Experimental Designs

• Research design with more power to control for
  time
• Pre-test post-test
• O1 O2 O3 X O4 O5 O6
• Pre-test post-test with control group
• O1 O2 O3 X O4 O5 O6
• O1 O2 O3 O4 O5 O6

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Did you bring your lab coat?

• Considering true experiments are close to
  impossible or unethical in political science, we
  need to apply science differently.
• Hence, this is why we in political science often
  use Quasi-experimental or non-experimental
  research designs

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Quasi-Experimental

• Quasi-experiments The researcher does not have
  control over the experiment, rather the
  experiment occurs in a natural setting.
• Quasi-experimental design are typical in
  economics, sociology, public administration,
  urban planning, political sciences, etc.

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Quasi-Experimental

• A prominent example of this type of research is
  arguably by Samuel Huntington, who argues that
  Latin American immigration, especially Mexican,
  is altering US culture for the worse.
• He essentially predicts that the United States
  will be a divided, less productive, society,
  ruining the past culture that has made the United
  States great.

http//www.foreignpolicy.com/story/cms.php?story_i
d2495
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Quasi-Experimental

• Huntington points out the following X variables
• Proximity of Mexico, Latin America to USA
• Former ties to Mexico
• Magnitude of recent wave of immigration
• Duration of recent wave of immigration
• Illegality

He does this by observing what is going on today.
It is crucial that one understands his
assumptions and evaluates what he claims as
evidence for his theory