1. Pre-post Double Blind Placebo Control Group Design
Chapter 8
Pre-post Double Blind Placebo Control Group
Design
Pre
Post
Treatment
(experimental)
Placebo Control
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2. Faulty Research Designs One Group After-only Designs
one measure of the DV, obtained after treatment
is given.
Problems:
Pre
Post
Treatment
(experimental)
Placebo Control
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3. One Group Before After (Pre-post) Design
Like the pre-post placebo control design, without the placebo control.
Problems:
Pre
Post
Treatment
(experimental)
Placebo Control
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4. Non-Equivalent Control Group
a control group that has not been obtained by
random assignment.
e.g., matching, logical comparisons, frequency distribution control.
Randomization – only means by which unknown extraneous variables can be controlled.
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5. Requirements of True Experimental Research Design.
- Comparison being made between 2 or more conditions of an IV.
The difference between these conditions is produced by the researcher.
All other confounds are controlled by ensuring that they are 1) eliminated, 2) effect all conditions equally or 3) are measured so their effects can be accounted for in the comparison.
All measures are unbiased.
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6. Why use a pretest within subjects control condition
Increased sensitivity – can use matching techniques to reduce variance (i.e., lowers sx
Control for Ceiling Effects
- can the treatment have an effect?
Gives Measure of Initial Position.
Can see if initial position determines
treatment outcome.
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7. Can determine initial comparability of between
group comparisons (useful for nonequivalent
control group designs)
Pre
Post
Treatment
(experimental)
Placebo Control
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8. If your research question is that the IV
causes a change – a pre-test control is
the logical control group.
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9. Between Participants - After Only Design
Compares Treatment Group to Control Group
Different subjects in each condition
Individual difference confounds.
Pre
Post
Treatment
(experimental)
Placebo Control
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10. Control Individual Difference Confound by: __________
If Random Assignment is not used then this
is a non-equivalent Posttest-only design.
Pgs 246 to 255 (Factorial Designs) will NOT be on Exam 3.
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