In corpus linguistics, the term ‘keyness’ has gained a specific meaning in recent years by which it refers to the extent to which text(s) show a specific stylistic profile when compared with another set of texts. Specifically, the term has been used when analysing the lexical profile of an author or author(s) in direct comparison with that of another group. By this means it has been possible to show how the style of an author or authors is distinctive vis à vis others of his/her time (one typical application). This distinctiveness is the ‘keyness’ of the texts by the individual(s) in question. ‘Keyness’ is quantified by measuring the positive or negative differences in the lexis of author(s) vis à vis the lexis of the texts in a reference corpus with which the former is compared.

The following screen shots illustrate how keyness can be measured. For this exercise two word lists were generated, one with a text by one author and one with texts by a group of authors. The latter word list is that of the ‘reference corpus’ and the former is that of the author whose ‘keyness’ compared to the group is being determined. The fictitious example demonstrates that the single author’s use of lexis varies with respect to the group of authors, mostly positively but also negatively in a few cases. The third list on the bottom of the first screen shot shows the combination of the two input word lists (upper left and right of the screen). The difference column shows positive figures, some negative ones and a few values of zero where the single author has terms which do not occur in the reference corpus. Row three also shows the opposite, i.e. a word which only occurs in the reference corpus but not with the single author.

The grid generated by the ‘keyness’ module of Corpus Presenter can be exported to an Excel table and there a chart can be generated which demonstrates visually the differences in lexis between the single author and the group of authors just discussed.