Frequency-based (the right answer) ------------------------ p(positive) = 3/6 = 0.5 p(negative) = 3/6 = 0.5 p( I | positive ) = 4/13 = 0.308 p( hated | positive ) = 1/13 = 0.0769 p( that | positive ) = 2/13 = 0.154 p( movie | positive ) = 1/13 = 0.0769 p( loved | positive ) = 3/13 = 0.231 p( it | positive ) = 2/13 = 0.154 p( I | negative ) = 4/13 = 0.308 p( hated | negative ) = 3/13 = 0.231 p( that | negative ) = 2/13 = 0.154 p( movie | negative ) = 1/13 = 0.0769 p( loved | negative ) = 1/13 = 0.0769 p( it | negative ) = 2/13 = 0.154 p(I loved it | positive)= p(I | positive) p(loved | positive ) = p(it | positive) p(positive) = 4/13 * 3/13 * 2/13 * 0.5 = 0.005462 p(I thought I hated it but loved it | positive ) = 0 because p(thought | positive) = 0. This is why we need to smooth! Presence-based (close, but NOT the right answer) p(positive) = 3/6 = 0.5 p(negative) = 3/6 = 0.5 p( I | positive ) = 3/3 = 1.0 p( hated | positive ) = 1/3 = 0.333 p( that | positive ) = 2/3 = 0.667 p( movie | positive ) = 1/3 = 0.333 p( loved | positive ) = 3/3 = 1.0 p( it | positive ) = 2/3 = 0.667 p( I | negative ) = 3/3 = 1.0 p( hated | negative ) = 3/3 = 1.0 p( that | negative ) = 2/3 = 0.667 p( movie | negative ) = 1/3 = 0.333 p( loved | negative ) = 1/3 = 0.333 p( it | negative ) = 2/3 = 0.667