Clustering Overview

As we have learned in the partitioning section, the goal of partitioning was to render the DSM lower triangular as much as possible. The reason was due to the significance of upper-diagonal marks, which represented feedback information flows. This situation arises whenever the matrix elements represent a set of project tasks (i.e. task-based DSM). On the other hand, when the DSM elements represent design components (i.e. component-based DSM) or teams within a development project (i.e. team-based DSM), the goal of the matrix manipulation changes significantly form that of partitioning algorithms. The new goal becomes finding subsets of DSM elements (i.e. clusters or modules) that are mutually exclusive or minimally interacting subsets. This process is referred to as "Clustering".

In other words, clusters absorb most, if not all, of the interactions (i.e. DSM marks) internally and the interactions or links between separate clusters is eliminated or at least minimized.

As a simple example, consider a development process that includes seven participants as shown in the DSM, below. Note that the interactions between different participants are also shown in the DSM. If we were to form several development teams within this project, what will be the number of teams required and the membership of each team?

Clustering the DSM for this project will provide us with insights into optimal team formations based on the degree of interactions among participants.

If the above DSM was rearranged in the following manner (as shown below). One possible team assignment is:

Team 1: participants 1 and 6

Team 2: participants 4 and 5

Team 3: participants 2, 3, 4 and 7.

Note that by making participant 4 a member of both teams 2 and 3, we were able to absorb more interactions internally within a team.

In another example, consider the following component-based DSM for an automobile Climate Control System (Pimmler and Eppinger, 1994).

The above DSM was rearranged such that the following module structure was apparent. 

Clustering the "X" marks along the diagonal of the DSM resulted in the creation of three "chunks" for the Climate Control System. The "chunks" are (Pimmler and Eppinger, 1994):

1. Front End Air Chunk.
2. Refrigerant Chunk.
3. Interior Air Chunk.

A Clustering Algorithm

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