An Empirical Study of Second Order Rotatable Designs under Tri-Diagonal Correlated Structure of Errors Using a Pair of Partially Balanced Incomplete Block Type Designs
Keywords:Rotatability, correlated errors, incomplete block designs
In this paper, following the works of Das (1997, 1999 and 2003), Rajyalakshmi and Victorbabu (2014, 2016 and 2018), second order rotatable designs under tri-diagonal correlated structure of errors using a pair of partially balanced incomplete block type designs (PBIBD) is suggested. Here we study the variance function of estimated response for different values of tri-diagonal correlated coefficient () and distance from the center (d) for various factors. This method gives designs with less number of design points than the corresponding second order rotatable designs (SORD) under tri-diagonal correlated structure of errors using pairwise balanced designs (PBD) and balanced incomplete block type designs (BIBD).