Comments on: Visualizing Bayes’ theorem

By: Amlan

Amlan — Tue, 15 Jun 2010 13:01:36 +0000

Really “Great” Job. Keep doing such good job, humanity will be enriched by people like you. Hats off to You!!

By: viky

viky — Wed, 10 Feb 2010 05:57:55 +0000

this proof was awesome.

By: Franco

Franco — Mon, 14 Dec 2009 01:02:31 +0000

Good visual explanation. I used it to work out a probability but don’t know if the professor is going to reject it.
Thanks.

By: Mark

Mark — Wed, 09 Dec 2009 01:58:57 +0000

Just wanted to convey my thanks.
I am teaching this subject to undergrads at a Chinese university and found your explanations and visuals a huge help.

By: Riley

Riley — Thu, 26 Nov 2009 22:09:59 +0000

Can someone help me with this question?
One fifth of customers entering a certain Future
Shop store are under 20 years old. 5% of these under 20 year olds make a purchase over $500,
and 10% of the customers 20 years or older make a purchase over $500. What is the probability
that is a major purchase is made, it was by a person 20 years or older?

By: Bayes and Probability « A Diary

Bayes and Probability « A Diary — Sun, 11 Oct 2009 13:12:39 +0000

[...] want to explain the calculation by Venn diagrams but someone else beats me to it http://oscarbonilla.com/2009/05/visualizing-bayes-theorem/ There’re links to others’ presentations so pick your favorite. What I think in terms [...]

By: Truecrimson

Truecrimson — Sun, 11 Oct 2009 11:26:26 +0000

You beat me to it! I got the idea of thinking about Bayes’ theorem by Venn diagrams by reading Reza’s An Introduction to Information Theory.

By: Dan Weisberg

Dan Weisberg — Fri, 02 Oct 2009 17:47:04 +0000

This is one of the best explanations I’ve found. Perhaps we can see if I really understand it by trying a real world problem I’m wrestling with.

Here’s the data:
– The odds of a chest pain (CP) being caused by a heart attack is 40%.
– The odds of a CP being caused by other factors (anxiety, depression, etc.) is 60%.
– The odds of a heart attack occurring to a female above age 50 is 80%.
– The odds of a heart attack occurring to a female under age 50 is 20%.

I am presented with a 24 year old female who says she is having chest pain. What is the probability that her chest pain is caused by a heart attack? Is it 0.4 x 0.2 = 0.08?

Also, 78% of patients having heart attacks present with diaphoresis (sweating), so 22% of patients having heart attacks don’t sweat. This female is not sweating, so are the odds of her having a heart attack 0.22 x 0.08 = 0.0176?

Thank you!

By: Usman

Usman — Wed, 16 Sep 2009 17:35:56 +0000

Beautiful explanation. I was searching for something that would help me explain it to undergrads…thanks a bunch.

By: Bill

Bill — Sun, 23 Aug 2009 22:57:21 +0000

May want to check the book by Wonnocott and Wonnocott. They have a visual way of explaining Bayes Theorem

By: CHARLY

CHARLY — Sat, 22 Aug 2009 10:19:10 +0000

Great work dude….I was banging my head to develop intuition on Bayes theorem. Now I got the idea clearly…

Thank u very much..

By: jozsef

jozsef — Fri, 14 Aug 2009 19:31:13 +0000

Very nice artice article in every meaning of the word. Have you publised elsewhere?

By: pinki

pinki — Fri, 14 Aug 2009 09:23:00 +0000

that’s a really appealing way of expressing Bayes’ theorem
how would the venn-diagram be if the conditional probability of A
didn’t depend on B i.e P(A/B)=P(A) ?

By: desiNerd

desiNerd — Sun, 19 Jul 2009 10:46:45 +0000

thank you very much…very nice article…

desiNerd,
IITKGP

By: Tapan Bagchi

Tapan Bagchi — Fri, 17 Jul 2009 01:48:19 +0000

Professor Oscar,

You are a great prof! You set a benchmark for us trying-to-be’s.

A question. When can I write

P(AB/R) = P(A/R) + P(B/R) ?

What conditions need to be imposed on A, B and R?

Thanks Professor!

Tapan Bagchi at the Indian Institute of Technology Kharagpur