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rgap

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Oct 31, 2011, 3:37:33 PM10/31/11
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hi.

in this question

http://www.youtube.com/watch?v=DjvGl1qRVdE&feature=related

why its not P(SPAM) = (9+1)/(24+2) ???????????????

benoît person

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Oct 31, 2011, 5:22:02 PM10/31/11
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Hi,

Because, by "spam" we are talking about "message" not "word". So, when you count, you have 3 spams messages for a total of 8 messages, not 9 spam-words for a total of 24 words.


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Benoit Person
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benoît person

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Oct 31, 2011, 5:24:46 PM10/31/11
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Even if we were counting "words", your formula would be wrong, because it would be : "9 + 1 / 24 + 1*size_of_the_vocabulary". And, "size_of_the_vocabulary" would be 13 if you were considering "word". Here we use "2" because a message is a spam or not.

2011/10/31 benoît person <benoit...@gmail.com>

Anders Alm

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Oct 31, 2011, 5:36:38 PM10/31/11
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Because this question is focusing on any random message from the list as a whole, not the words.

In this case I see P(SPAM) as; if you pick any defined message from the list (without knowing what message you pick), what is the probability of it being spam.

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