CS-431: Q3 question on Naive Bayes

Hi!

I am having trouble understanding the answer to the following question:

I used the following reasoning to answer the question:

And that is why I answered that D6 is Space. But the correct answer is Animal. What is the reasoning / mathematics behind?

Sincerely,

Re: Q3 question on Naive Bayes

by Jean-Cédric Chappelier - Monday, 18 November 2024, 09:53

Your

$P(w|C)$ are wrong: this is not the the proba that a document (of that class

$C$ ) contains the word (nor contains that many words (count)), but the probability that this word appears in that class, which can be estimated (MLE) by number of occurrences of

$w$ (in

$C$ ) divided by the total number of words in class

$C$ .
For instance

$P(\text{cat} | \text{Space})$ is estimated by

$\frac1{10}$ ,

$P(\text{Dog} | \text{Space})$ by

$\frac4{10}$ .