DSM Tutorial - Observations / Issues with Building DSMs
Important observations / issues considered when collecting DSM data
You cannot do all data gathering by talking to yourself!
Passing out forms to collect DSM data did not prove to be very reliable. Instead, face-to-face interviews with the right experts is recommended to fill out these forms.
People are reasonably accurate in answering what "information" they need before they can do their job, and where to get this information. However, they are less accurate/reliable when it comes to knowing where does their information go and who uses it.
There is a tendency for engineers to want/ask for as much information as possible before making a decision about a parameter. This will tend to over-populate the DSM with unnecessary marks.
There is a tendency for engineers to rely on past experiences when making judgement as to what information is needed to fully determine a given parameter (in a current / ongoing project). This may result in ignoring important marks in the DSM.
High level abstraction or decomposition of a system might oversimplify the design process and tend to ignore important sub-system interactions that might be apparent at a lower abstraction level. On the other hand, with finer system decompositions we run a risk of diminishing the intuitiveness provided by the DSM as it becomes increasingly difficult to identify important sub-system interfaces. This difficulty can be overcome by building a hierarchy of DSMs at different levels of abstraction. By that we mean, build a high level DSM first (that may contain all different subsystems as line items only). Then, for each line item in the previous DSM hierarchy, build a separate DSM (which explodes each line item in previous DSM into a separate DSM). This process of DSM explosion can be cascaded down (as shown in the figure below) enough until certain desired interactions are apparent at the lowest level. Finally, the lowest level DSMs can be aggregated to form a complete system DSM.
[above figure is taken from Sabbaghian et al. (1998)]
