A Note on Second Order Rotatable Designs under Intra-Class Correlated Structure of Errors Using a Pair of Partially Balanced Incomplete Block Type Designs

  • Bejjam Re. Victorabu Department of Statistics, Acharya Nagarjuna University, Guntur, India
  • Vellanki Prasanthi Department of Mathematics, SRK Institute of Technology, Vijayawada, India
  • Kottapalli Rajyalakshmi Department of Mathematics, KLEF (KL deemed to be University), Guntur, India
Keywords: Response surface designs, rotatability, robustness, incomplete block designs


In this paper, following the works of Das (1997, 1999 and 2003), Rajyalakshmi (2014), Ravindrababu  and Victorbabu (2018), Victorbabu and Ravindrababu (2019), second order rotatable designs (SORD) under intra-class correlated structure of errors using a pair of partially balanced incomplete block type designs is suggested. Here we study the variance function of estimated response for different values of intra-class correlated coefficient  and distance from the center  for various factors. This method gives designs with less number of design points than the corresponding SORD under intra-class correlated structure of errors using central composite designs, pairwise balanced designs, balanced incomplete block designs and symmetrical unequal block arrangements with two unequal block sizes in some cases.


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