12_AltApproaches - Have pre-post measures for 2 groups, but...

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Alternative Approaches Specialized Designs
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1. Single Subject Designs A is baseline. B is treatment. Add and remove treatment to find effect. Common designs: A-B, A-B- A, A-B-A-B 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Trial 8 6 4 2 0 BPM (bar presses per minute) Single Subject Responses ABAB Design A B A B
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Interrupted Time Series Time 120 100 80 60 40 20 0 Weekly Totals 14000 12000 10000 8000 6000 4000 2000 Actual Predicted Effects of 9/11 on volunteering
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2. Quasi-experimental Designs Quasi-experiments have treatment groups, but non-random assignment to treatment. E.g., classroom as group assignment in ed study . Non-experimental or pre-experimental study: Single group pre-post study. Measure at T1, treat group, measure at T2. Effect? T1 T2 T1 T2 T1 T2 No causal conclusion is possible here.
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Quasi-experimental Design (2) Pre-experimental design lacks a control group. Other examples? Corporate training.
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Quasi-Experiment (3) Nonequivalent control group design.
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Unformatted text preview: Have pre-post measures for 2 groups, but no random assignment to group. Control is best match we can do. Post Pre Time 180 150 120 90 60 30 Mean Packages Per Hour Quasi-Experiment Nonequivalent Control Group Store 1 (Control) Store 2 (Experimental) Note. Pretest means are different. Look for what would be an interaction in a true experiment. Quasi-experiment (4) • No treatment effect Post Pre Time 180 150 120 90 60 30 Mean Packages Per Hour Quasi-experiment Store 1 (Control) Store 2 (Experimental) Means for both groups increase similarly. Review • How do you show an effect with a single-subject design? • How do you show an effect with a quasi-experiment? • What is the major design difference between a true experiment and a quasi experiment? • What is the difference in what you can infer between the true experiment and the quasi-experiment?...
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This note was uploaded on 05/21/2011 for the course PSY 3213 taught by Professor Staff during the Fall '08 term at University of South Florida.

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12_AltApproaches - Have pre-post measures for 2 groups, but...

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