1. A computer-implemented method of determining values of keywords in an internet search comprising: receiving keywords entered by at least one user for a plurality of search terms; obtaining information about converted transactions associated with a plurality of searches, the plurality of searches having been performed based on the keywords; estimating a general transaction probability; estimating unigram keyword probabilities; determining conditional probability values associated with the keywords based on the converted transactions; estimating keyword transaction probabilities based on the general transaction probability, the unigram keyword probabilities, and the conditional probability values; and generating expected transaction values based on the keyword transaction probabilities, wherein the expected transaction values are generated according to: E ⁡ ( T ❘ k , S ) = P ⁡ ( T ❘ k , S ) * ∑ ∀ t ⁢ R ⁡ ( t ❘ k , S ) C ⁡ ( t ❘ k , S ) , where C(t|k,S) is a non-zero value.
1. A computer-implemented method of determining values of keywords in an internet search comprising: receiving keywords entered by at least one user for a plurality of search terms; obtaining information about converted transactions associated with a plurality of searches, the plurality of searches having been performed based on the keywords; estimating a general transaction probability; estimating unigram keyword probabilities; determining conditional probability values associated with the keywords based on the converted transactions; estimating keyword transaction probabilities based on the general transaction probability, the unigram keyword probabilities, and the conditional probability values; and generating expected transaction values based on the keyword transaction probabilities, wherein the expected transaction values are generated according to: E ⁡ ( T ❘ k , S ) = P ⁡ ( T ❘ k , S ) * ∑ ∀ t ⁢ R ⁡ ( t ❘ k , S ) C ⁡ ( t ❘ k , S ) , where C(t|k,S) is a non-zero value. 5. The method of claim 1 further comprising: ranking the keywords based on a conditional transaction completion probability; and providing a recommendation of a subset of the keywords to optimize marketing objectives.