Multi-Dimensional studies (MD) is a new statistical approach to language variation developed by Doug Biber. The methodology involved in this approach means that for the first time, using corpora of spoken and written language from different periods, we can demonstrate how language varies from one type of text to another, for example, how American style varies from British. Doug Biber begins with a discussion of the methodology required and emphasises the new insights into language variation and use that can be gained from the MD approach.