Class 27 – Thursday Dec 5, 2012

Next to last class. I will have the students work the Strogatz breast cancer screening exercise, starting with a little communal setup. Course evaluations at the end of the class.

Good class (I think). Just reading the Strogatz paragraph giving breast cancer incidence, true positive and false positive rates was a challenge. Then I asked them to take the doctor’s quiz: given a + test, what’s the probability of cancer?

We worked the problem using natural frequencies (a strategy introduced a long time ago and mostly forgotten) to figure out that the answer was about 10%. Many were stunned/incredulous. Which made the effort worthwhile.

Concluded with qualitative analyses of similar situations

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