Recovery of inter‐block information in cross‐over trials

For cross-over designs, we show that one can recover information on direct and/or residual treatment effects from an inter-block (patients as blocks) analysis as is done in an incomplete block design. By combining the intra- and inter-block estimates, we obtain the generalized least squares estimate. In analysing cross-over trials, we recommended this approach provided the between-patient variance component can be estimated efficiently.