This paper deals with the problem of finding the robustness of of Balanced Incomplete Block design with repeated blocks for the missing of three blocks involving all non-repeated blocks as well as distinct blocks. We have obtained A-efficiency for four different cases under the unavailability of three blocks. It is observed that BIB design with repeated blocks is fairly robust against the unavailability of three non-repeated blocks which are distinct. Finally it is also concluded after investigation that as the number of common treatment increases among the missing blocks the efficiency of residual design decreases.
Keywords: Robustness, A-Efficiency, Balanced incomplete block design with repeated blocks.