Design Structure Matrix - Design

Design

A DSM is a square matrix. The cells along the diagonal represent the system elements, which are often labeled in the rows to the left of the matrix and/or in the columns above the matrix. The off-diagonal cells are used to indicate relationships between the elements. Reading across a row reveals what other elements the element in that row provides outputs to, and scanning a column reveals what other elements the element in that column receives inputs from. Alternatively, the rows and columns may be switched (without a change of meaning).

Two main categories of DSMs have been proposed: static and time-based. Static DSMs represent systems where all of the elements exist simultaneously, such as components of a machine or groups in an organization. Static DSMs are usually analyzed with clustering algorithms. In time-based DSMs, the ordering of the rows and columns indicates a flow through time: earlier activities in a process appear in the upper-left of the DSM and later activities appear in the lower-right. Terms like “feedforward” and “feedback” become meaningful when referring to interfaces. Time-based DSMs are typically analyzed using sequencing algorithms.

DSMs stem from diverse roots. A static DSM is equivalent to an N-square diagram or an incidence matrix. A time-based DSM is akin to a precedence diagram or the matrix representation of a directed graph. The time-based DSM (and the "DSM" term itself) originated with Don Steward, who coined the term “design structure matrix” in the 1960s. Steward's DSM grew from the use of matrices to solve mathematical systems of equations. Christopher Alexander presented a similar matrix-based design method in his 1964 book Notes on the Synthesis of Form.