Steve Eichert on 31 Jul 2008 14:17:44 -0700


[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]

Re: collective intelligence - bayes theorem help

  • From: Steve Eichert <steve.eichert@gmail.com>
  • To: "philly-lambda@googlegroups.com" <philly-lambda@googlegroups.com>
  • Subject: Re: collective intelligence - bayes theorem help
  • Date: Thu, 31 Jul 2008 17:11:19 -0400
  • Authentication-results: mx.google.com; spf=pass (google.com: domain of steve.eichert@gmail.com designates 209.85.132.245 as permitted sender) smtp.mail=steve.eichert@gmail.com; dkim=pass (test mode) header.i=@gmail.com
  • Cc: Philly Lambda <philly-lambda@googlegroups.com>
  • Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlegroups.com; s=beta; h=domainkey-signature:received:received:x-sender:x-apparently-to :received:received:received-spf:authentication-results:received :dkim-signature:domainkey-signature:received:received:references :message-id:from:to:in-reply-to:content-type :content-transfer-encoding:mime-version:subject:date:cc:x-mailer :reply-to:sender:precedence:x-google-loop:mailing-list:list-id :list-post:list-help:list-unsubscribe:x-beenthere; bh=AZqD4DsPV16alOZeBwOpqt28gqVNWOv09nkr46GwkAA=; b=LHabdKfhy9gY52sFNhzyOFWg80QaTQmHnsHUaKiNPkwHXsqSV6BubpausWZtSvjKXU CpZsQKEyb8M/VDf/hnMuwYgBSzet2iJldvFjLFhpBtc2hZJU3ZB8LRoaT3MV5jKBGSeV bS15Suvn0ku0cAa9k5tSBMgh+mScENx0vNNSY=
  • Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:references:message-id:from:to :in-reply-to:content-type:content-transfer-encoding:mime-version :subject:date:cc:x-mailer; bh=sbvwqPHqNr7MQySsm14P1uxBb8DfvDwse/4b1jw7Hvg=; b=dH8a4+Ve13ftZxiWB4VOIXMPEO+UMzuAZ3j9a5F1kzcxC/Kc0wfCHbpC6t1H/m+gMB WYY4SBs1RLiInf6Lo9WOEmx6Zj3wLyYimlqedmNTwAxw25tSuXySc6EYQvTW1KOYVzez 0EjLY9msPOZDpdoWmYmrto2yJptVYvSXJBZAc=
  • Mailing-list: list philly-lambda@googlegroups.com; contact philly-lambda+owner@googlegroups.com
  • Reply-to: philly-lambda@googlegroups.com
  • Sender: philly-lambda@googlegroups.com


Right, and what if in my example, state doesn't impact the probability at all. If belonging to Philly lambda is the key determining factor then taking state into account only throws us out of whack.

I'll have to take a look at what's available in excel, perhaps it will help me understand.

Steve

On Jul 31, 2008, at 4:15 PM, yegg <gabriel.weinberg@gmail.com> wrote:


So there would be a 50% chance that Jonathan follows Toby given that he's from NJ. So from what I understand, in order to find the probability that Jonathan follows Toby given that he's in Philly Lambda, and he's from NJ I
would multiple the probabilities of each together.

1 * .5 = 50%

So I think that I could say that there's a 50% chance that a person from NJ and in Philly Lambda follows Toby. Is that correct given this simplistic
approach, or am I doing something wrong?

This assumes the attributes are completely independent of each other.
Take the case of language attributes, e.g. who uses Perl and Lisp.
Suppose both were 50% (of the people who follow Toby).  By this logic,
the final probability would be 25%.  But what if the exact same people
who use Lisp also use Perl, then the real answer would be 50% because
the additional attribute tells you nothing.  It would only be 25% if
they were completely independent.



I don't know anything about the other stuff you mentioned (Bayes classifier, regression analysis) so I'll have to try and read a bit about them and see
how I may be able to use them.

You can do this in Excel.  The help is helpful.  Basic linear
regression is built in.  To do more advanced stuff, do Tools->Add Ins,
add Analysis and Solver.  Then you can do Tools->Data Analysis.