What is the prior probability P(C = ‘no’) ? how i can find prior probability in this table ? Naïve

Hashmat_Sediqi123

BalazsBaranyRM

Hi,

in the RapidMiner Academy there are multiple videos about Naive Bayes.

Here's RapidMiner founder Ingo explaining the algorithm:
https://academy.rapidminer.com/learn/article/naive-bayes-are-we-playing-golf-today

If you look at the model description, it says:

SimpleDistribution

Distribution model for label attribute Play

Class no (0.357143)
4 distributions

Class yes (0.642857)
4 distributions

These are exactly the fractions of the values in the entire distribution - the prior probability of the class in the training data.

The numbers you see in the table can be interpreted as "the fraction of the data where Outlook = overcast and Play = yes". 

Regards,
Balázs

Telcontar120

If you look at the table, you can see that the probabilities shown will total to 1 (not accounting for rounding) for each class for each attribute.  So there are 4 possible values for the outlook attribute (rain, overcast, sunny, unknown) and 2 classes (yes/no) and the sums for each set will total to 1.