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Exercises for Therac-25

Analyzing Therac-25

This exercise uses a modified version of Robert Collins and Keith Miller's ParaMedic Ethics procedure. Collins and Miller recommend a procedure to use in evaluating a decision. We are not here evaluating any particular decision, but we can use their method to help us understand the obligations, rights, costs, and benefits for each of the parties in the system. This exercise will require students to read the case on the website with some knowledge of the method they will be using, so they can take relevant notes as they read. Thus, the best approach to this exercise requires introducing the modified paramedic ethics procedure in one class, assigning the exercise and case as homework, and then spending the next class period discussing student’s conclusions.

Alternatively, students might be assigned the case to read for homework and then introduced to the method of analysis in the subsequent class. If this approach is taken, be sure to have the case available in class (either on a computer with a projector or in printouts for each student) to aid recall.

There are several approaches to having students read the case for this exercise. You might have them read all the case section but exclude the accident reports. Once students have gone through the paramedic procedure based on their knowledge, you might then introduce them to one or more of the accidents. Does this new information change their assessments of the case? You might give some students partial information (e.g. just the background sections) and others more extensive information. This too is likely to produce differences in their analyses of the case. Alternatively, you might use small sections of the case (e.g. just the background) early in a course and add information about the case as the course progresses.

Each of these approaches are likely to produce differences in the way the case is analyzed by students. These differences help make it clear how important a comprehensive view of a case is.

Our modified paramedic ethic procedure consists of 4 phases. The basic analysis consists of phases 1 and 2, in which the basic relationships among the important stakeholders in the case are outlined. The phases that construct and judge the various alternative scenarios can be done as many times as you wish for each set of actions you think are important. To make this go faster, you might assign groups to construct and present their analysis of the duties and rights of each of the main stakeholders presented in the case: AECL, FDA, hospitals, operators, and patients.

Gather data

  1. List the relevant stakeholders. Start with some of the groups mentioned in the socio-technical system page. However, do not end there. Notice that our accident victims, the patients, are not included. Other important groups may also be omitted (e.g. "the public"). The ImpactCS framework provides you with a useful guide to different levels of stakeholders that you might overlook.
  2. Outline the duties and rights the stakeholders have toward each other. This is best done with a drawing of each stakeholder with arrows indicating duties one owes to other and rights one has. Duties always have targets, one has duties to a particular person (even to oneself). Rights may appear to be free floating (e.g. not to be harmed) but they can often be translated into duties that others have toward the individual (avoid harming X). The ImpactCS framework provides a useful guide to outlining these duties and rights. Use the list of ethical issues to remind yourself of rights and duties in the range of likely ethical domains.

Analyze the data

  1. List the relevant opportunities and vulnerabilities that each stakeholder had in the case. This is the beginning of what Collins and Miller call a utilitarian ethical analysis. Who is being helped and harmed? What advantages or opportunities does each party receive in this case? What costs or dangers, or vulnerabilities does each party experience?
  2. Determine to what degree each stakeholder's duties were fulfilled or neglected.
  3. Determine to what degree each stakeholder's rights were violated or protected, and by whom.

Construct an Alternative Scenario.

  1. Construct a promising alternative for some set of actions for a significant actor (e.g. reporting procedures in AECL, FDA procedures, hospital treatment procedures, safety analysis procedures by AECL). For some hints about alternative sets of actions, see the exercises about computer control choices and about reporting procedures.

Judge the Alternative

    1. Judge the alternative's effect on each stakeholders' opportunities and vulnerabilities and on each stakeholders' duties and rights.
    2. Imagine each stakeholder in a negotiation with other stakeholders about whether the alternative should be adopted or not. This certainly helps uncover disagreements about the opportunities and vulnerabilities for each party. One interesting way to stage this negotiation is to have parties that initially represent each stakeholder attempt to don a "veil of ignorance" about which stakeholder they might be when the alternative is adopted. If you might be randomly assigned to any of the stakeholder roles in the case, how would this affect your evaluation of the alternative?
    3. Rank the alternative with other alternatives for that set of actions. An alternative does not have to be perfect, or even optimal, to be better than the others.

Collins, W. R. & Miller, K. W. (1992). Paramedic ethics for computer professionals. Journal of Systems and Software, 1-20.