Some comments about full factorial designs

7 Some comments about full factorial designs 

Full factorial designs have been especially useful for describing the effects of qualitative factors, factors that are measured on nominal or ordinal scales. This environment of qualitative factors is where factorial designs originated. Because all possible factor combinations are investigated in a full design, the results using qualitative factors are essentially historical and have little, if any, predictive ability. 

Full factorial designs are also useful for describing the effects of quantitative factors, factors that are measured on interval or ratio scales. This is how factorial designs are often used today. Because the factors are quantitative (e.g., 20 lbs or 40 lbs of catalyst, 1 hour or 2 hours reaction time), the results have some predictive ability (e.g., what would the results be with 50 lbs of catalyst and 2.5 hours reaction time ). 

Full factorials are often praised because they can be used to reveal factor 

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