This category of editing often elicits groans and winces from business writers because it summons Images of painful schoolroom exercises, unreasonable entrance examinations, and other unpleasant academic events that many would like to forget. It also elicits groans and winces from business readers because writing that is grammatically incorrect will cause misreadings, misunderstandings, and embarrassment. Of course, these problems will interfere with the writer's attempts at engaging and maintaining the readers' attention. Grammatical problems present readers with a form of competition that is similar to noise on an audio recording: just as one competes for the listener's attention to the music, so the other competes for the reader's attention to the message. Fortunately, grammar is a relatively simple matter, at least to the extent that it is primarily concerned with the formation and agreement of words. It is also an important matter, with strong implications for establishing an ethos of credibility and professionalism. 1
Although writers can inspect their writing for correct grammar at any time during composition, they will probably do well to wait until they have edited for conciseness, word choice, word order, and punctuation. Checking for grammatical problems earlier than this can easily result in a wasted effort, in correcting expressions that will either be deleted, reordered, or substituted. However, once these matters have been settled, writers are ready to turn their attention to grammar, and to the practical points that follow.
Readers expect consistency and care in the writing they read. They expect writers to be consistent with matters of meaning and careful about changing meaning without cause. Because of this, writers who violate rules of agreement appear to their readers in a variety of unflattering ways -- as uneducated, uncaring, or unable, to name only a few.
Happily, the principle behind grammatical agreement is easy enough to understand, although it is violated in practice even by the most careful writers. The principal rule of agreement requires a match between associated words. For example, the first sample sentence below shows normal agreement between the subject and verb