This paper is concerned with using the digital computer as an aid to the solution of a class of multivariable design problems and reports some experience. The input to the computer is a set of design variables and a set of interactions between these variables, while the output consists of a hierarchy of groups of highly interacting variables. Both the preparation of the input and the interpretation of the output depend on subjective decisions by the designer using the computer. A specific application was therefore investigated in which different sets of inputs were compiled by three different designers, using 18, 38, 58 and 185 variables. The four outputs were analysed to compare their usefulness as a design aid in proportion to the effort required for their preparation. An IBM 7044 computer was used and a guide is given for the estimation of program running times on this machine.