Number: singular or plural?

Errors in which singular subjects govern plural verbs, or vice versa, are examples of what grammarians refer to as errors of concord. Concord – agreement – between subject and verb is the most important type. Mistakes occur most commonly with either…or, neither…nor, none, in lists, and with collective nouns (particularly when the noun is separated from the verb by a long clause). The error that many people seem to know about, but that is the least important, is the one made with the word DATA.

EITHER…OR, NEITHER…NOR, EACH

In Either Mr A is a liar or Mrs B is psychotic the verb is repeated and there is no confusion: the verb is singular. It is also singular if one or the other is the subject of the same verb: Either Mr A or Mrs B is psychotic.

Neither one nor (either links with or; neither with nor) the other is an ideal induction agent. These constructions cannot be applied to more than two choices.

When one of the choices is singular and the other plural, write the plural noun second: Neither the doctor nor the nurses are responsible…. The plural noun then governs the verb by the principle of proximity.

In speech, the plural is more natural when either…or or neither…nor is used.

Each implies a consideration of things taken one at a time and is singular: Each patient was asked….