The Design Structure Matrix for Project Planning

The mind mapping approach just described is an excellent complement to traditional project management tools like the work breakdown structure for helping identify the tasks that need to be executed to complete a project. Other project management planning tools such as Gantt charts and precedence diagrams (both discussed in Chapter 5) were devel­oped primarily to coordinate the execution of these tasks. These tools were originally developed to help manage large but relatively well-structured projects such as construc­tion projects and ship building. However, in some cases, such as new product development projects, the issue of information flows can be as important as the sequencing of tasks. In essence, traditional project management planning tools help identify which tasks have to be completed in order for other tasks to be started. Often, however, a more important issue is what information is needed from other tasks to complete a specific task?

To address the issue of information flows, Steven Eppinger (2001), a professor at MIT’s Sloan School of Management, proposes the development and use of a Design Structure Matrix (DSM). The first step in developing a DSM is to identify all the project’s tasks and list them in the order in which they are typically carried out. This list of tasks makes up both the rows and columns of the DSM. Next, moving across one row at a time, all tasks that supply information to the task being evaluated are noted. When the DSM is completed, all the tasks that provide information that is needed to complete a given task can be determined by looking across that particular task’s row. Likewise, moving down a particular task’s column shows all the other tasks that depend on it for information.

An example DSM corresponding to a project with six activities is shown in Figure 3-10. According to the figure, completing activity c requires the gathering of information from activities b and f. Furthermore, the figure indicates that activities c and f both depend on information from activity b.

As the example illustrates, a key benefit of constructing a DSM is the ability to quickly identify and better understand how information is needed. It can also highlight potential information flow problems even before the project is started. For example, all the X’s above the diagonal in Figure 3-10 are related to situations where information obtained from a subsequent task might require the rework of an earlier completed task. To illustrate, in the second row we observe that activity b requires information from activity e. Since activity e is completed after activity b, activity b may need to be revisited and reworked depending on what is learned after completing activity e.

The DSM also helps evaluate how well the need to coordinate information flows has been anticipated in the project’s planning stage. To make this assessment, a shaded box is added to the DSM around all tasks that are planned to be executed concurrently. For example, the DSM would appear as shown in Figure 3-11 if it had been planned that tasks c, d, and e were to be done concurrently. Also notice that in Figure 3-11, any remaining entries above the diagonal of the matrix are highlighted as potential rework by replacing each X with an O.

In examining Figure 3-11, there are two potential rework situations. Fortunately, there are a couple of actions that can be taken to minimize or even eliminate potential rework situations. One option is to investigate whether the sequence of the project activ­ities can be changed so that the potential rework situations are moved below the diago­nal. Another option is to investigate ways to complete additional activities concurrently. This latter option is a bit more complex and may necessitate changing the physical loca­tion of where the tasks are completed.

Source: Meredith Jack R., Mantel Jr. Samuel J., Shafer Scott M., Sutton Margaret M. (2017), Project Management in Practice, John Wiley & Sons, Inc. 3th Edition.