Issues with mining unstructured data
Humans can read, parse, and understand unstructured text/documents more easily than computer-based programs. Some of the reasons why text mining is more complicated than general supervised or unsupervised learning are given here:
Ambiguity in terms and phrases. The word bank has multiple meanings, which a human reader can correctly associate based on context, yet this requires preprocessing steps such as POS tagging and word sense disambiguation, as we have seen. According to the Oxford English Dictionary, the word run has no fewer than 645 different uses in the verb form alone and we can see that such words can indeed present problems in resolving the meaning intended (between them, the words run, put, set, and take have more than a thousand meanings).
Context and background knowledge associated with the text. Consider a sentence that uses a neologism with the suffix gate to signify a political scandal, as in, With cries for impeachment and popularity...
