fa13-cs188-lecture-17-1PP

# Value if we act now assume we see that e e value

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Unformatted text preview: Forecast Forecast distribution F P(F) good 0.59 bad 0.41 W U leave sun 100 leave rain 0 take sun 20 take rain 70 Value of Informa)on   Assume we have evidence E=e. Value if we act now:   Assume we see that E = e . Value if we act then:   BUT E is a random variable whose value is unknown, so we don t know what e will be   Expected value if E is revealed and then we act: a {+e} P(s | +e) U {+e, +e } a P(s | +e, +e ) U {+e} P(+e | +e) P( ­e | +e)   Value of informa)on: how much MEU goes up by revealing E ﬁrst then ac)ng, over ac)ng now: {+e, +e } a {+e,  ­e } VPI Proper)es   Nonnega)ve   Nonaddi)ve (think of observing Ej twice)   Order ­independent Quick VPI Ques)ons   The soup of the day is either clam chowder or split pea, but you wouldn t order either one. What s the value of knowing which it is?   There are two kinds of plas)c forks at a picnic. One kind is slightly sturdier. What s the value of knowing which?   You re playing the lokery. The prize will be \$0 or \$100. You can play any number between 1 and 100 (chance of winning is 1%). What is the value of knowing the winning number? Value of Imperfect Informa)on?   No such thing   Informa)on corresponds to the observa)on of a node in the decision network   If data is “noisy” that just means we don’t observe the original variable, but another variable which is a noisy version of the original one VPI Ques)on   VPI(OilLoc) ? DrillLoc U   VPI(Scou)ngReport) ?   VPI(Scout) ?   VPI(Scout | Scou)ngReport) ?   Generally: If Parents(U) Z | CurrentEvidence Then VPI( Z | CurrentEvidence) = 0 Scout OilLoc Scou)ng R...
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## This note was uploaded on 12/22/2013 for the course CS 188 taught by Professor Staff during the Fall '08 term at Berkeley.

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