This kind of analysis may serve, for instance, to test the authenticity or
authorship of a text. In much biblical or Shakespearean scholarship, the
received text is compared with possible sources, or competing versions are
compared with each other, in order to establish a canonical text. Editorial
overlays are peeled away to reveal the presumed original text. If authorship
is in doubt, stylistic comparison with other texts is used to support arguments
for or against various contenders. Where the purpose for which a text was
edited is known, analysis of input and output can establish whether that
purpose has been achieved. If a text has been edited for a particular readership,
comparison with the original can show whether the edited version is in
fact more suitable for the readership than the original. Texts are often
re-written for learners, whether foreigners or children, according to readability
formulas. The study by Davison et al. (1980) indicates how writing to
such formulas does not necessarily produce a text suitable for the target
readership.