Stylistic changes caused by a change in mode of composition can be investigated only if computational stylistics can accurately detect style variation. Multiple methods and approaches are introduced here that easily distinguish authors from each other and identify intra-authorial differences, such as differences caused by chronology, genre, and the sub-styles of multiple characters or narrators. These methods are also proven on subtler intra-textual variations and special cases like imitation, pastiche, and collaboration. The methods that are shown to succeed on these difficult tasks will be able to detect the effects of changes in mode of composition if they are significant.