Introduction to Research Design

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Introduction to Research Design
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What Is Research Design?

• The structure of research

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Elements of a Design

• Observations or measures
• Treatments or programs
• Groups
• Assignment to group
• Time

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Observations or Measures

• Symbolized with an "O". Subscripts are used to
  distinguish different combinations of measures
  only if this is necessary.

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Treatments or Programs

• Symbolized with an "X". Subscripts are used to
  indicate different programs or combinations of
  programs.

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Groups

• Each group of interest on its own line .

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Assignment to Groups

• R Random assignment
• N Nonequivalent groups
• C Assignment by cutoff

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Time

• Left-to-right movement denotes the passage of
  time.

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Design Notation Example
R O X O R O O
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Design Notation Example
R O X O R O O
Time
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Design Notation Example
R O X O R O O
Os indicate different waves of measurement.
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Design Notation Example
Vertical alignment of Os shows that pretest and
posttest are measured at same time.
R O X O R O O
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Design Notation Example
X is the treatment.
R O X O R O O
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Design Notation Example
There are two lines, one for each group.
R O X O R O O
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Design Notation Example
R O X O R O O
R indicates the groups are randomly assigned.
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Design Notation Example
R O1 X O1, 2 R O1 O1, 2
Subscripts indicate subsets of measures.
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Design Notation Example
R O X O R O O

• Pretest-posttest (before-after)
• Treatment versus comparison group
• Randomized experimental design