Factorial designs at two levels Ch. 5
Factorial Design Two levels All possible combinations. Two factors and variables. Two level simple interpretation, few runs per factor Quantitative or qualitative factors Factors can interact (nonzero correlations!)
Example Three factors on clarity of film (wax formula): A: emulsifier, B: emulsifier, C: catalyst concentration. Each factor at two levels: 2 3 factorial design.
Example 1
Example 2
Example 3
Interactions: TK=(33-13)/2 =10 TK=( )/2 =10 TCK=[(35-31)/2- (14-12)/2]/2 =0.5 CKT=[(-3+4)/2- (-7+6)/2]/2 =0.5
Example 3 TCK=( )/4=0.5
Example 3
if each factor was replicated a different number of times: Each estimated effect is a difference between two averages: v(effect)=(1/8+1/8)s 2 =8/4=2 Standard error=sqrt(2)=1.4
Ejemplo 3