Fractional-factorial designs effects interpretation

Multiple-factor interaction effects can be used to determine a critical effect value for the interpretation of full and fractional factorial designs [29] ... 

Merck also proposed recently an expert system called Ruggedness Method Manager for ruggedness tests of chromatographic assay methods. The system uses fractional factorial designs. Besides the factors to be examined, interactions that possibly also could be relevant have to be defined by the user. The system then calculates a design in which the main effects are not confounded with one of the specified interactions. The interpretation criterion to identify statistically significant effects is not known to the authors of this chapter. 

Assume that you have run a fractional factorial design 2 (4 = 12, 5 = 13, 6 = 23), showing that the variables 1 and 5 are probably not significant, the following interpretation of the estimated effects can be attempted. 

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