June 2012
Intermediate to advanced
320 pages
8h 50m
English
Problem 30
Simpson's Paradox (1951)
Problem. Consider the three events X, Y, and Z. Suppose
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Prove that it is still possible to have
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Solution. Using the law of total probability, we have
where
and
. Therefore,
We now consider the sign of Eq. (30.3). Let
,
, and
. Then

where . Therefore, is negative if .
The algebra can mask the real implication of the three ...
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