HELLO READER! This is a version of a presentation on Decision Based Design (DBD) presented at the April '97 face-to-face meeting. The original ideas were developed at the January '97 face-to-face meeting. What you are about to read are the notes from the April '97 presentation with commentary from meeting attendess highlighted.

Decison-Based Design (DBD) is One Perspective on Design

There are many perspectives through which we can study design. DBD is one of the many perspectives. We believe that it has value as a perspective and are examining this perspetive on design to learn its complete value.

Understanding Decision-Based Design (DBD)

What is the purpose of attempting to understand DBD?

Commentary: The main point is that decision-making is an important part of design that can't be ignored during the design process and that may yield insight into how to perform the design process more effectively.

Begin with Engineering Design

To answer the question, "What is DBD?", we must first answer the question, "What is design?". Since we are approaching this from an engineering background, we prefer to answer the question, "What is engineering design?".

Commentary: Since DBD can be applied in a broader context than just engineering design, we may wish to broaden our focus here.

What is DBD?

In DBD we view design as a decision-making process involving:

Commentary: This simple statement generated a great deal of discussion and highligts the need for work on developing an agreed-upon lexicon of terms for use in any research area. The discussion centered upon the questions, "What is the difference between uncertainty and risk?".

Uncertainty involves the inability to have all known facts at one's disposal when making a decision. On the other hand, risk is a condition in which there are no known facts. Risk involves predictions.

One meeting participant suggested that DBD involves ambiguity independent from uncertainty.

There are many sources providing the values necessary and present in the decision-making proces. We identify them as follows:

A DBD Process

We begin our discussion of the DBD process by observing that design is a decision-making process. The tools used in the design process include representations, modelling, analysis, languages, etc.. The role that decisions and decision-making play during the application of each of these tools are of great interest to the DBD researcher. It is easy to agree with the statement, "Design activities involve decision-making." However, we believe that not all design activities are decision activities.

We normally characterize a design process as a series of activities, and DBD is no different. The generic decision-based design process includes the following steps:

These observations support the view that there may be activities in the design process that are decision activities but do not require the same type of decision-making as that used for a selecting a final design -- which necessarily involves values, uncertainty, and risk assessment.

It appears then, that there is a fuzzy front end -- a soft boundary -- delineating the beginning of the hard core, value-laden DBD process. Once the option space exists, then the next three steps take place with a concern for values, uncertainty, and risk.

What is Not DBD?

Commentary: Our original intentention in this discussion was to contrast the above definitions of the DBD process to other design methods popular in the research community. This way we could answer the question, "What is not DBD?" However, our meeting participants quickly directed us to the more appropriate question, "Where and how does DBD fit in?

Where Does DBD Fit in?

Decision-based design is a framework by which the design activity can be understood, structured, managed, and evaluated. A good way to define a science of decision-based design is to determine how this perspective on design fits into the overall body of knowledge on design theory and methodology. We can then compare the DBD approach to others.

Several perspectives on design have emerged from Open Workshop discussions:

Where do we go From Here?

This introduction to decision-based design (DBD) should give Open Workshop visitors some background for commenting on the discussion. To do so, please visit our "Open Research Questions" page to enter your comments.

If you have comments or suggestions, email me at lschmidt@eng.umd.edu