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Subject-Verb Agreement

Subject and verb must agree. The following paragraph is from CBE, 5th ed. (p. 39):

Most nouns are either singular or plural in both form and sense and require a verb of the same number (the insect is, insects are). Some are plural in form but singular in sense (kinetics is). Some are collectives that are singular in form but may be either singular or plural in sense (school, herd, family). When a collective noun is used as a subject, its verb is singular when you believe that the subject acts as a unit, but its verb can be plural if the subject is thought of as individuals: The committee resolves that...; the committee believe that....

The above paragraph was written as a guide for authors; the copy editor must remember that where a decision must be made concerning whether the subject acts as a unit or as individuals, the choice of the author, based on the scientific meaning of the sentence, must be accepted. Even in a sentence in which the meaning appears clear, there is a chance that a verb change can change the meaning of the sentence.

False Singulars

Be on alert for Latin-derived nouns that have plural forms not ending in "s", such as data/datum, media/medium, criterion/criteria, phenomenon/phenomena, corrigendum/corrigenda, erratum/errata. Always use the plural verb for the plural form.

The most widely used culture media are...
The data support the view that...
Very few data were available...

False Plurals

Some words may be mistakenly taken for plurals, since they end in a "plural" "s" or "es." They take a singular verb.

measles
mumps
mathematics
genetics
kinetics

Collective Nouns

This can be tricky and requires some attention. Note that when the group is regarded as a unit, the singular verb should be used.

Twenty percent of time is spent on...

An average of 15 for this period is about as good as one can expect.

However, when the individual members of the group are emphasized, a plural verb is 
needed.

Ten percent of the staff work flexible hours.

A wide range of phenomena are involved.

Only a fraction of the total species of any given period are likely to leave fossil traces.

An average of 15 men were used in both experiments.

A number of the patients were given a placebo... 

Use the plural verb for plural units of measure but not after fractional units of measure.

Fifteen milliliters were added to the mixture.

After 0.7 ml was added...

Many authors use parenthetical plurals. For consistency, use the following generally accepted rule: when an "s" or "es" is added in parentheses to a subject or subjects, the verb should be singular because the "s" or "es" is parenthetical.

The name(s) of the editor(s) of the book in reference 2 is unknown.

Compound Subject Joined by Either-Or/Neither-Nor

In such cases, the verb agrees with the subject closer to the verb.

Neither staphylococci nor streptococci were responsible...
Neither the hospital nor the physicians were responsible for the...
Neither she nor they are involved.
You or he is the person who... 

Intervening Phrase

The singular verb is preferred when an intervening phrase is introduced by "as well as", "together with", "in addition to", etc. Also, even if a plural intervening phrase follows the subject, the verb must agree with the subject, whether it is singular or plural.

Liver failure, in addition to massive hepatic enlargement, was not described in HIV-positive patients.

The editor, as well as the reviewers, believes that the article...

Elliptical Constructions Involving Change in Number

When a verb is omitted as understood, a change in the number of subject may lead to a subject-verb disagreement.

bad

Her tests were run and her chart updated.
After the diagnosis was made, physical therapy sessions begun.

good

Her tests were run, and her chart was updated.
After the diagnosis was made, physical therapy sessions were begun.

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last edited 07/30/03