Book excerpt: Similarities and differences between speech and writing have been the subject of innumerable studies, but until now there has been no attempt to provide a unified linguistic analysis of the whole range of spoken and written registers in English. In this widely acclaimed empirical study, Douglas Biber uses computational techniques to analyse the linguistic characteristics of twenty three spoken and written genres, enabling identification of the basic, underlying dimensions of variation in English. In Variation Across Speech and Writing, six dimensions of variation are identified through a factor analysis, on the basis of linguistic co-occurence patterns. The resulting model of variation provides for the description of the distinctive linguistic characteristics of any spoken or written text andd emonstrates the ways in which the polarization of speech and writing has been misleading, and thus enables reconciliation of the contradictory conclusions reached in previous research.