Quadratic dynamic matrix control consists of the on-line solution of a quadratic programming (QP) problem. Blocking and condensing (B & C) are techniques that consider a reduced set of future manipulated variable and predicted output values in the QP problem by assuming them to be constant over intervals. B & C improve the controller robustness and reduce the QP computation time. There is a need for a systematic design methodology for the selection of B & C intervals. Wavelet transforms provide a suitable framework for developing a B & C design methodology. B & C in the time domain and in the wavelet domain are compared. It is shown that time domain B & C is edge driven, while that using wavelets is interval driven. A new design procedure for interval-driven B & C using information theory and sensitivity analysis is developed. The design procedure is applied to the Shell process control problem. Simulation results are discussed and some design guidelines are provided. B & C are also examined in the context of using move suppression factors.