1. 1 Experimental Design

2. 2  Single Factor - One treatment with several levels.  Multiple Factors - More than one treatment with several levels each.  The Treatment is the independent variable (X) which we manipulate (change the level).  The Response (which we observe/measure) is the dependent variable (Y).

3. 3 Single Factor (One Way)  Completely Randomized Design  Between Subjects Design (Nested)  Test objects (subjects) randomly assigned to only one level of the treatment.  Easiest to design, understand, calculate, analyze.  Relatively robust and free of restrictive statistical assumptions.  Disadvantages -  Requires large number of subjects  Lacks sensitivity in detecting treatment effects

4. 4 Single Factor - continued  Randomized Complete Block Design  Within Subject Design (Repeated Measures)  Test objects (subjects) participate in all levels.  Advantages -  Require fewer subjects  More sensitive in detecting differences  Disadvantages -  Adherence to strict statistical assumptions  Subjects may undergo “learning effect”

5. 5 Fixed Effects & Random Effects  Fixed Effects - Treatment levels set to specific values. Results should only be generalized to these specific levels.  Random Effects - Treatment levels randomly selected from a population of many different levels. Results may be generalized to the entire range of levels for that particular treatment.  Note: A combination of fixed and random effects is sometimes referred to as a “mixed design”.

6. 6 Multiple Factorial Design  Two or more independent variables  Factors = Treatments  Each different factor (treatment) may have several different levels.  Trial is an experiment at a specific level of a specific treatment.

7. 7 Factorial Design  Completely Randomized Factorial Design  Between Subjects Design (Nested)  Each subject participates in only one trial.  Randomized Complete Block Factorial Design  Within Subject Design (Repeated Measures)  Each subject receives all levels of all treatments.  Mixed Factor Design  Between & Within Subject Design (Nested/Repeated)  Subject participates in some, but not all levels.