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Authorship studies alone cannot prove authorship, but can provide evidence for
or against a given theory. For example, we can analyze Shakespeare's plays to
determine his writing style, before testing whether a given sonnet actually does
originate from him.
A more modern use case is that of linking social network accounts. For example,
a malicious online user could set up accounts on multiple online social networks.
Being able to link them allows authorities to track down the user of a given
account—for example, if it is harassing other online users.
Chapter 9
Another example used in the past is to be a backbone to provide expert testimony
in court to determine whether a given person wrote a document. For instance, the
suspect could be accused of writing an e-mail harassing another person. The use of
authorship analysis could determine whether it is likely that person did in fact write
the document. Another court-based use is to settle claims of stolen authorship. For
example, two authors may claim to have written a book, and authorship analysis
could provide evidence on which is the likely author.
Authorship analysis is not foolproof though. A recent study found that attributing
documents to authors can be made considerably harder by simply asking people,
who are otherwise untrained, to hide their writing style. This study also looked at
a framing exercise where people were asked to write in the style of another person.
This framing of another person proved quite reliable, with the faked document
commonly attributed to the person being framed.
Despite these issues, authorship analysis is proving useful in a growing number
of areas and is an interesting data mining problem to investigate.
Attributing authorship
Authorship attribution is a classification task by which we have a set of candidate
authors, a set of documents from each of those authors (the training set), and a set
of documents of unknown authorship (the test set). If the documents of unknown
authorship definitely belong to one of the candidates, we call this a closed problem.
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