Investigation into The Robustness of Balanced Incomplete Block Designs

A set of measures is developed which indicate the robustness of a Balanced Incomplete Block Design (BIBD) against yielding a disconnected eventual design in the event of observation loss. The measures have uses as a pilot procedure and as a tool to aid in design selection in situations in which significant observation loss is thought possible. The measures enable non-isomorphic BIBDs with the same parameters to be ranked. Investigation of a class of BIBDs suggests there is some correspondence between robustness against becoming disconnected and rankings associated with A-efficiency.