This investigation of verb contractions (e.g.I'm and it's) and NOT-contractions (don't and haven't) uses two samples of British newspaper text from 1994 and 1961. The 1994 material, compiled for this study, is carefully matched to the press categories of the well-known LOB corpus of written British English.
The study explores the use of contracted forms in British newspapers today and also considersthe quantitative and qualitative changes since the early 1960s. In this process, it analyses and categorizes instances of blocked contraction. In addition, some implications for the teaching of English as a foreign language are outlined.
The variation between contracted and uncontracted forms is analysed with regard to factors such as the character of the subject, the function of the verb, the sentence type, occurrence in quoted and nonquoted contexts, and textual position-headline, introduction or conclusion. The analysis is mainly based on the contraction ratio of each contraction, defined as the number of contracted forms divided by the number of potential contracted forms of the same type, whether realized or not.
Verb contractions have a higher frequency than NOT-contractions, but a lower ratio of contraction. Five verb contractions are prominent in the 1994 newspapers:I'm, that's, you're, it's and I've, the first with a contraction ratio of about 50% and the last two about 30%. Unlike most previous studies, verb contractions with noun subjects are also investigated, e.g. Daddy's. The contraction ratio of such forms is only about 4%. The most frequently used NOT-contractions are don't, doesn't, didn't, can't, couldn't, won't and wouldn't. Don't is the `normal' form, used more often than do not, not only in questions and imperatives but also in statements.
As expected, quoted speech turns out to be an important factor, especially for verb contraction. Nearly all verb forms are at least twice as likely to be contracted in quoted as in nonquoted contexts. In quoted speech, contractions with the first-person pronouns I and we as subjects are most common. In nonquoted contexts, contractions with third-person pronoun subjects prevail.
About 30% of the contractions in nonquoted contexts are found in headlines, or in introductory and concluding sentences of articles. In these positions, contractions may have the function of making articles seem more personal and more reader-accessible.
The most noticeable increases in the 1994 data compared to those of 1961 concern contraction of is, particularly in nonquoted contexts, where the form it's is used seven times as often.
Uppsala: Acta Universitatis Upsaliensis , 1998. , 270,  p.
1998-05-16, hörsal 1, Ekonomikum, Kyrkogårdsgatan 10, Uppsala, Uppsala, 10:15