Selecting Defining Contrasts and Confounded Effects in p n-m Factorial Experiment

Fractional factorial designs presented in standard tables are not always suitable when some factors are more likely than others to interact. If the fraction is small compared to the total number of treatments, the selection of defining contrasts to generate a design meeting specified requirements is not straightforward. A systematic procedure is given for selecting defining contrasts and confounded effects in p n-m factorial designs (where p ≥ 2 is prime).