7. The method of claim 1 , further comprising: sorting the textual data of the target domain into groups based at least in part on an occurrence of a particular identifier in the textual data of the target domain, wherein the particular identifier is labeled with a known sentiment; creating an additional identifier based at least in part on an occurrence of a term that is used a predefined number of times in one of the groups; and assigning the known sentiment to the additional identifier.
7. The method of claim 1 , further comprising: sorting the textual data of the target domain into groups based at least in part on an occurrence of a particular identifier in the textual data of the target domain, wherein the particular identifier is labeled with a known sentiment; creating an additional identifier based at least in part on an occurrence of a term that is used a predefined number of times in one of the groups; and assigning the known sentiment to the additional identifier. 8. The method of claim 7 , further comprising assigning a first weight to the identifiers and a second weight to the additional identifier.