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In the class of two-level non-regular designs, Plackett-Burman ([14], 1946) designs have a special place. These designs have been widely used as screening designs because of their relative simplicity of use. Wang and Wu ([16],1995) observed that these designs possess certain hidden projection properties which are bestowed by the complexity of their partial aliasing relationships. They attributed the success of Hamada and Wu's ([9],1992) strategy for entertaining and estimating twofactor interactions from Plackett-Burman (PB) type designs to the hidden projection property. In this paper, we have used the hidden projection property of the 24-run PB design to propose an alternative to the design suggested by Mclean and Anderson ([13],1984). The proposed design performs better in terms of increased degrees of freedom efficiency and reduced run size. We have also drawn non-isomorphic interaction graphs making D and Ds efficiency as the underlying criterion. [ABSTRACT FROM AUTHOR]

Taguchi (1959) introduced the concept of split-unit design to sort the factors into different groups depending upon the difficulties involved in changing the levels of factors. Li et at (1991) renamed it as split-plot design. Chen et at (1993) have given a catalogue of small designs for two- and three-level fractional factorial designs pertaining to a single type of factors. Aggarwal et al. (1997) have given a catalogue of group structure for two-level fractional factorial designs developed under the concept of split-plot design. In this paper, an algorithm has been developed for generating group structure and possible allocations for various 3n-k fractional factorial designs. [ABSTRACT FROM AUTHOR]