this post was submitted on 25 Nov 2023
1 points (100.0% liked)

Machine Learning

1 readers
1 users here now

Community Rules:

founded 1 year ago
MODERATORS
 

hi everyone, I could not understand answer. I found 1/4 from table. answer is 1/2. thanks everyone.

https://preview.redd.it/tht330mp7h2c1.png?width=939&format=png&auto=webp&s=2084932c8e79929563ddc757f012fce0c040453c

you are viewing a single comment's thread
view the rest of the comments
[–] mofoss@alien.top 1 points 1 year ago (2 children)

P(K=1) = 1/2

P(a=1|K=1) = P(a=1,K=1)/P(K=1) = (1/4)/(1/2)=1/2

P(b=1|K=1) = P(b=1,K=1)/P(K=1) = (1/8)/(1/2)=1/4

P(c=0|K=1) = P(c=0, K=1)/P(K=1) = (1/4)/(1/2)=1/2

P(a=1, b=1, c=0, K=1) = 0

P(a=1, b=1, c=0, K=0) = 1/8

[0.5 * 0.25 * 0.5] / (0 + 1/8) = (1/16) / (1/8) = 1/2

For conditionals, convert it into joints and priors first and THEN use the table to count instances out of N samples.

P(X|Y) = P(X,Y)/P(Y)

:)

[–] Terrible_Button_1763@alien.top 1 points 1 year ago (2 children)

At the very least your calculation does not agree with your formula of P(X|Y) = P(X,Y)/P(Y).

How is the numerator a calculation of P(X,Y)? [0.5 * 0.25 * 0.5] is P(a = 1 | K =1 ) * P(b = 1 | K = 1) * P(c = 0 | K = 1) which is (in Naive Bayes) P(X|Y) by Naive Bayes and not P(X, Y).

[–] mofoss@alien.top 1 points 1 year ago (1 children)

Uh not sure what Fubini's theorem is, I just use the equivalence of P(X|Y)P(Y) = P(Y|X)P(X) = P(X,Y)

[–] Terrible_Button_1763@alien.top 1 points 1 year ago (1 children)

That's not what the questions is asking. And that's not Bayes' rule. The denominator is not even calculating P(Y) under Naive Bayes.

Hmm, maybe machine learning is not just import tensorflow/pytorch/llm.

[–] mofoss@alien.top 1 points 1 year ago (1 children)

Features are independent when conditioned on the dependent is pretty much what I know about Naive Bayes, I personally don't care for the semantics.

Also the last time I was using naive bayes was grad school 7 years ago so things are fuzzy, sorry

Save it for your next submission, friend.

[–] mofoss@alien.top 1 points 1 year ago (1 children)

Oh wait I made a typo, OP ignore my answer 😅

[–] mofoss@alien.top 1 points 1 year ago
[–] Kruki37@alien.top 1 points 1 year ago (1 children)

Seems like you dropped one of the 1/2s from the numerator. Maybe I’m missing something but the answer looks like 1/4 to me as your workings show

I rate your answer 🌶️🌶️🌶️🌶️🌶️ / this dumpster fire.