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# DNA fingerprinting

Read the Star Tribune article on OJ and DNA, and the Independent and New Scientist articles on DNA fingerprinting.

### Problems

1. What does Prof. Starrs mean when he says, `An expert witness can testify that it means it's him or her to the exclusion of anyone else in the world.'

2. What does Mr. Cunningham mean when he says, `It can be as conclusive as millions and billions, depending on the statistical data'?

3. Assume that a match is established in the Simpson case and the experts say that there is 1 chance in a million of such a match by another person. Do you think that this evidence alone would result in a conviction? Should it?

4. Do you think that there should be a national DNA data base in the United States?

5. In the New Scientist article it is stated that the posterior odds are the prior odds multiplied by the DNA match probability (Assuming that, if guilty, the probability of a match is 1). How do you see that this is the case? Do you think you could explain it to a jury?

6. Explain the example in the Independent article in terms of odds ratios.

7. Peter asked for the probability that 40"yes" to our poll if no one in the class ever chewed gum. How could you find this probability?

8. Could you also find the probability that no one in the class has ever chewed gum given that 40

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laurie.snell@chance.dartmouth.edu