SEVEN-FACTOR CENTRAL COMPOSITE DESIGN ROBUST TO A PAIR OF MISSING OBSERVATIONS

In this work, the seven-factor central composite design (ccd) is studied in respect of a pair of missing values using the minimax loss criterion. It was observed empirically that seven-factor central composite design with , , , and is robust at and variance robust at . We also observed that the loss effect of missing a pair of factorial points is a decreasing function of increasing , while the loss effect of a pair of axial points is a decreasing and increasing function of increasing . The loss effect of missing a factorial and axial points has no specific direction of increase or decrease on increasing values. In this work, the seven-factor central composite design (ccd) is studied in respect of a pair of missing values using the minimax loss criterion. It was observed empirically that seven-factor central composite design with , , , and is robust at and variance robust at . We also observed that the loss effect of missing a pair of factorial points is a decreasing function of increasing , while the loss effect of a pair of axial points is a decreasing and increasing function of increasing . The loss effect of missing a factorial and axial points has no specific direction of increase or decrease on increasing values.