Alternate Method for the Robustness of the Block Design of Block Sizes two against the Loss of Whole Blocks

The usual procedure for indentifying the block design to be connected is rank of C matrix (information matrix) should be (v ? 1), if this violates then design becomes disconnected. Several authors obtained robustness criteria against the loss of one block or more than one blocks based on connected property. Because connectedness is one of the important criteria to find the robustness of the residual design. Tsai and Liao (2013) discussed the minimum break down criteria and connectedness criteria of block design to obtain the robust design against the lost of whole block. In this investigation, we have developed other criteria, which is alternate method of Tsai and Liao (2013) to find connectedness of the block design based on block information matrix, Fd of the block design of size two. Further, we have also observed as numbers of blocks are being deleted, the overall A-efficiency of the residual design decreases.. KEYWORDS :Block design, Residual design, Robust design , Connectedness.