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4. TECHNIQUES FOR COLLABORATIVE KNOWLEDGE ACQUISITION

As the size and complexity of expert systems increase, many experts and several knowledge engineers are needed in the knowledge acquisition process of an expert system project. Techniques described above may be employed in collaborative knowledge acquisition by interviewing (or observing) a team of experts one at a time. The "serial" knowledge acquisition process causes the following problems. (1) It is a lengthy and time-consuming process. (2) Problem-solving strategies and the knowledge used by experts may conflict with each other. Knowledge engineers should not assume that they have sufficient knowledge in the domain to try to solve these conflicts, which must be resolved by the individual experts through several iterations. (3) Experts do not have chances to stimulate each other's thinking to surface the underlying knowledge they use. (4) The integration of problem-solving expertise acquired from individual experts into a knowledge base is still needed even if there is no conflict among experts' opinions. The missing links of various expertise in the domain have to be acquired from the experts themselves.

Brainstorming is a group method for developing ideas and exploring their meaning. It promotes the identification of a number of considerations related to a problem domain. It is designed to stimulate thinking and generate ideas in such a way that each individual may develop his or her train of thought or expand upon other individuals' thinking. Interactions in the form of exchanging thoughts are encouraged to enrich the outcome of the group process. Brainstorming also can be used to help experts and knowledge engineers discover areas that require special attention in the problem-solving process. With multiple experts working as a team, brainstorming can help prevent immediate confrontation, reduce inhibited behavior, and resolve conflicting views.

To use the brainstorming technique for knowledge acquisition, a stimulus must be introduced to domain experts. This takes the form of a question, a statement, or a problem scenario. For instance, a brainstorming stimulus might be "describe specific steps in a consultation session." Each participant (i.e., domain expert) of the brainstorming session suggests one idea in response to the question by writing it on a piece of paper or entering it into a computer file. These suggestions are then randomly assigned to participants, who are asked either to follow the same train of thought or come up with new ideas. The process is repeated until the rate of idea generation slows down to a threshold rate and the pool of ideas is collected. At this point the process moves on to analyze and organize these ideas.

An electronic form of the brainstorming technique has been used in group sessions to define a problem scope, to identify possible solutions, and to develop a heuristic classification scheme. This technique provides a useful tool for acquiring knowledge from multiple experts. Conflicts can be identified and resolved during the brainstorming session and interactions among experts create a synergy of expertise.

Nominal Group Technique (NGT) is a method for structuring small group meetings that allows individual judgments to be pooled effectively and used in situations where there is uncertainty or disagreement about the nature of a problem and possible solutions. This technique is helpful in identifying problems, exploring solutions, and establishing priorities. It typically includes four steps: (1) silent generation of ideas in writing; (2) round-robin recording of ideas; (3) serial discussion of the list of ideas; and (4) voting. This problem-solving procedure reduces negative effects (i.e., nonparticipation, conflicts) that may be triggered by face-to-face interaction among team members. In a collaborative environment, such as a GDSS, the Idea Organization tool facilitates the first three steps of the NGT. A voting tool completes the fourth step. Knowledge engineers have found that a combination of group interaction and the Nominal Group Technique enhances the creativity and quality of the resulting solutions.

The Delphi technique uses a series of questionnaires to aggregate the knowledge, judgments, or opinions of experts (usually anonymous) to address complex problems. Individual contributions are shared with the whole group by using the results from each questionnaire to construct the questionnaire for the next round. One of Delphi's principal uses has been to make future projections and forecasts. It can also be used to identify goals and objectives, generate possible alternatives, establish priorities, reveal group values, gather information, and educate a respondent group. By keeping individuals separated and maintaining their anonymity, the Delphi technique reduces the influence of potentially dominant people, prevents the undue influence of the personalities of certain individuals and allows strangers to communicate effectively. It also allows for the participation of more people than could interact effectively in a group and prevents unproductive disagreements. Delphi is useful whenever it is desirable to have pooled judgment and when experts are geographically dispersed. This technique has been used to facilitate an expert system development project for target industry analysis. A hypermedia-based Delphi tool has also been developed for knowledge acquisition (Wolstenholme and Corben, 1994).

Focus group interviews is a technique developed in marketing research. It involves conducting intensive discussions of a team of consumers to generate ideas for new products or explore consumer reaction to new product concepts. The interviews are conducted by a moderator and consist of three stages: (1) establish rapport with the group, structure the rules of group interaction, and set objectives; (2) attempt to provoke intense discussion in relevant areas; and (3) attempt to summarize the groups' responses to determine the extent of agreement.

In the context of knowledge acquisition, a knowledge engineer, as the moderator, conducts a group meeting with a team of experts discussing the problem-solving strategies. The moderator must perform the difficult task of "guiding" the discussion into the relevant areas while exerting minimal influence on the content of the discussion. The interaction process induced by the group situation produces a number of potential advantages: (1) Snowballing -- Each individual is able to expand and refine his/her opinions in the interactions with the other members. (2) Stimulation -- A group interview situation is more exciting and offers more stimulation to participants than a standard-depth interview. (3) Security -- The security of being in a crowd encourages some members to speak out when they otherwise would not. (4) Individuals are not under any pressure to make up answers to questions.

This technique can be used in conjunction with the structured interviewing technique to force organization of the communications that take place between a knowledge engineer and experts. The structure provided by goals reduces the interpretation problems inherent in unstructured interviews and allows the knowledge engineer to prevent the distortion caused by domain expert subjectivity. It is more effective because it "forces the domain expert to be systematic in attending to interview tasks." However, the moderator can introduce biases in the interview by shifting topics too rapidly, verbally or nonverbally encouraging certain answers, failing to cover certain areas, and so forth. In addition, the interviews are usually taped and transcribed for further analysis, which can be very time-consuming.


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