Browsing by Subject "probability theory"

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    Visualizing DNA Proof
    (2015) Georgakopoulos, Nicholas L.; Robert H. McKinley School of Law
    DNA proof inherently involves the use of probability theory, which is often counterintuitive. Visual depictions of probability theory, however, can clarify the analysis and make it tractable. A DNA hit from a large database is a notoriously difficult probabi­li­ty theory issue, yet the visuals should enable courts and juries to handle it. The Puckett facts are an example of a general approach: A search in a large DNA database produces a hit for a cold crime from 1972 San Francisco. Probability theory allows us to process the probabilities that someone else in the database, someone not in the database, or the initial suspect, Baker, may be the perpetrator and obtain the probability of Puckett’s guilt. Given the clarity of this analysis, decisions that do not follow it deserve reversal as clearly erroneous.
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    Visualizing Trials with Large DNA Databases
    (Office of the Vice Chancellor for Research, 2015-04-17) GEORGAKOPOULOS, NICHOLAS L.
    Abstract: This essay seeks to help the reader understand the use of probability theory in assessing DNA evidence drawn from large databases. I first guide the reader through visualizing a slightly simpler paradox of probability theory, the rare disease test. I then offer a visual understanding of the Puckett setting: DNA evidence from a large database identifies an individual but a deceased prime suspect exists whose DNA is not available. Effectively, the court needs to ascertain the probability that the third of three possible worlds has materialized. In the first possible world, the prime suspect, Baker, is the perpetrator and the court observes a false positive. The second possible world has an unknown perpetrator and again the court observes a false positive. The third world has Puckett as the perpetrator and the court observes a true positive. It turns out that the resulting posterior probabilities are strongly but not overwhelmingly in favor of the third possibility, true guilt.