Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Experimental Design Complex Designs (cont.)Slide 8Slide 9Experimental DesignI. Definition of Experimental DesignII. Simple Experimental DesignIII. Complex Experimental DesignIV. Quasi-Experimental DesignV. Threats to ValidityExperimental Design - DefinitionControl over the sequence and proportion of the independent variable involving: 1) at least two conditions (i.e. an independent variable); 2) random assignment of subjects to conditions; and 3) the measurement of some outcome (i.e. dependent variableExperimental Design – Simple Designs2. Pre-Post-test Control Group Designs (t-test) E R O1 X -> O3 C R O2 -> O4 1. Post-test Control Group Designs (t-test) E R X -> O1 C R -> O2Experimental Design – Simple Designs (cont.)3. Soloman Four Group Design (t-test)E1 R X1 -> O1 C1 R -> O2 E2 R O1 X1 -> O3 C2 R O2 -> O4 4. Analysis of Variance (ANOVA) E1 R X1 -> O1 E2 R X2 -> O2 E3 R X3 -> O3Experimental Design – Complex DesignsMain EffectsInteraction Effects 1. Completely Randomized Designs (CRD) (This example is a 2x3 CRD)  C-E1 C-E2 C-E3 R-E1 O11 O12 O13 R-E2 O21 O22 O23Experimental Design Complex Designs (cont.)2. Incomplete Designs (IRD) Split Plot Design (This example is a 2x3 SPD) C-E1 C-E2 C-E3 R-E1 - O12 O13 R-E2 O21 O22 -Experimental Design Complex Designs (cont.)3. Repeated Measures Designs (RMD) Latin Square Design ( This example is a 4x4 LSD) O1 O2 O3 O4 O2 O3 O4 O1 O3 O4 O1 O2 O4 O1 O2 O3Experimental Design – Quasi Experiments1. One Shot Case StudyE O1 X ->O2 2. Non-Equivalent Control Group Design E O1 X -> O3 C O2 -> O4 3. Interrupted Time-Series DesignE O1 O2 O3 X O4 O5 O6Experimental Design - Threats to Validity1. History = confounding of IV over time2. Maturation = age / experience contaminate 3. Testing = subjects come to understanding IV4. Regression to the Mean = extreme scores regress5. Selection of Participants = non-random assignment6. Mortality = subject attrition7. Diffusion of Treatments = lack of control