Assigning Blame Exercise

Your response is due by 11:59pm on Sunday, Jan 31, as a single PDF file.

One of the most infamous errors in the history of software engineering comes from the story of a sometimes-lethal radiation therapy machine called the Therac-25. The banality of its problems are matched only by the lethal quality of their ill-effects.

Sadly, the problems with radiation therapy software have not gone away. A recent article in the New York Times describes problems with modern systems. Alert: The article makes for slightly gruesome reading; those with people who have undergone or will be undergoing similar treatment may find it especially disturbing.

Your homework is simple. First, read the above Times article. Then, analyze it. Arguably, the problems described in it can be attributed to operator error, software error, other causes, or some combination thereof. Your task is to assign blame. (If this seems simplistic, remember that ultimately, that is what juries of peers do.)

Tell us how you would apportion blame between operator error, software error, and any other causes you wish to list. Give us numbers (representing percentages). Also write at least one, but at most a few, paragraphs explaining your reasoning. If you introduce additional causes, please keep them concrete: i.e., avoid such vague and indirect causes as “the health-care system in America”, “the Obama administration”, or “fluoride in the water supply”.

Submit your write-up using the handin script:

/course/cs190/bin/cs190_handin blame