• A few comments on this section:
• More Definitions
• Recall:  Observational Study vs. Experiment
• Benefits of Designed Experiments over Observational Studies
• Dangers in Experimental Design
• Statistical Significance
• Comparative Experiments
• Comment on Comparative Experiments
• Example
• Confounding Variable
• Confounding Variable
• Two Common (but Weak) Design Formats
• Comments on the Two Common (but Weak) Design Formats
• Principles of Experimental Design
• Control:  A Closer Look
• Random Assignment:  A closer look
• Random Assignments, contd
• Replication:  A closer look
• Cautions about Experimentation
• Cautions about Experimentation, contd
• Types of Experimental Designs
• Types of Experimental Designs
• Types of Experimental Designs
• Ex:  Matched Pair Design
• Note on blocks:
• Example: Blocking
• Slide 28