Subject-verb agreement is one of the most fundamental and important grammar rules in English. It helps maintain clarity at the sentence level. Without subject-verb agreement, it is difficult to understand the sentence's meaning.
Subject-verb agreement means that the subject and the verb of a sentence agree or match in number—whether singular or plural. The subject determines whether the verb should be singular or plural. Singular subjects should have singular verbs, and plural subjects should have plural verbs. Another way to think about this is, in general, there must be one S at the end of either the subject or the verb.
The researcher studies the data.
Here, “researcher" is the subject of the sentence. “Studies" is the verb, the action the researcher is performing. Both the subject and the verb are singular, and so they agree. There is only one S: at the end of “studies." This is a grammatically correct sentence.
The researchers study the data.
This sentence is also grammatically correct. Both the subject and verb are plural. Only one word, “researchers," ends in S. The subject and verb agree.
The researcher study the data.
While “researcher" is singular, “study" is not. The subject and the verb do not agree. There is no S at the end of either word. This is a grammatically incorrect sentence.
The researchers studies the data.
Here, the subject is plural but the verb is singular. The subject and verb don't agree. Both words have S at the end. This is a grammatically incorrect sentence.
These example sentences are short, so it is easy to find the subject and verb to make sure they agree. Sometimes, in more complex sentences, subjects and verbs are separated by other words.
Researchers at the University of Cambridge who are working on a similar project studies the data.
In this example sentence, “Researchers" is still the subject, and the verb is “studies." Because the subject and verb are so far apart, it can look like “studies" is correct; it comes right after “project," which is a noun. However, it is not the subject of the sentence, the person, place, or thing doing the action. So, the subject and verb of this sentence do not agree and the sentence is grammatically incorrect.
Additionally, if the verb comes before the subject, subject-verb agreement can be harder to keep track of.
There is numerous instances of change with this therapy modality.
This example is incorrect because “instances" is plural and “is" is singular. The sentence should be:
There are numerous instances of change with this therapy modality.
Let's fix the following sentence: Researchers at the University of Cambridge who are working on a similar project studies the data.
Step 1: Identify the Subject and Verb
Reduce the sentence to its simplest meaning. In this case, that would be, “researchers studies." The subject is the person, place, or thing (researchers) doing the action, and the action is the verb (studies).
Step 2: Check for -s Endings
Only one (either the subject or the verb) of the identified words from step 1 should end in S. In this sentence, “researchers" ends in S. So does “studies." Because both words end in S, we know that this sentence needs to be edited for subject-verb agreement.
Step 3: Make Adjustments
Adjust the subject or the verb, depending on whether the subject should be singular or plural. Do this by adjusting the spelling of the word, usually adding or removing an S.
In this sample, there was more than one researcher, so we need to keep that word plural. That means we have to edit the verb. The correct sentence is therefore:
Researchers at the University of Cambridge who are working on a similar project study the data.
Reading a complex or confusing sentence aloud is a good tip. Often, we can hear if something is wrong with a sentence even if we can see it right away on the page.
Collective Nouns
Collective nouns are used for a group of individual people or things. They may look singular (i.e., no S at the end of the word), but can be treated as singular or plural, depending on the intended meaning or context of the sentence as a whole.
Some examples of collective nouns include:
Now, consider the following sample sentences:
The staff is happy.
The staff are all wearing different colors.
Both of these sentences are correct. However, the first sentence highlights the group as a whole, so it makes more sense to use a singular verb. The second sentence highlights the individuals within the group; in this context, it makes more sense to use a plural verb.
Commonly Mis-Numbered Words
Analyses (plural of analysis)
Incorrect: We performed several analysis.
Correct: We performed several analyses.
Appendices (plural of appendix)
Incorrect: The appendixes are listed in the back.
Correct: The appendices are listed in the back.
Bases (plural of basis)
Incorrect: The researchers covered all basis in preliminary trials.
Correct: The researchers covered all bases in preliminary trials.
Criteria (plural of criterion)
Incorrect: I ensured all criteria was met.
Correct: I ensured all criteria were met.
Crises (plural of crisis)
Incorrect: The crisises were difficult for the family to handle.
Incorrect: The crises was difficult for the family to handle.
Correct: The crises were difficult for the family to handle.
Curricula (plural of curriculum)
Incorrect: The curricula covers the spectrum of learning levels.
Correct: The curricula cover the spectrum of learning levels.
Data (plural of datum)
Incorrect: The data was varied.
Correct: The data were varied.
Diagnoses (plural of diagnosis)
Incorrect: The diagnoses is interrelated.
Correct: The diagnoses are interrelated.
Hypotheses (plural of hypothesis)
Incorrect: Not all hypothesis is proved.
Incorrect: Not all hypotheses is proved.
Correct: Not all hypotheses are proved.
Phenomena (plural of phenomenon)
Incorrect: The phenomena reveals a pattern.
Correct: The phenomena reveal a pattern.
Syntheses (plural of synthesis)
Incorrect: Synthesis lead to results.
Incorrect: Syntheses leads to results.
Correct: Syntheses lead to results.
Theses (plural of thesis)
Incorrect: Multiple thesis was drafted.
Incorrect: Multiple theses was drafted.
Correct: Multiple theses were drafted.
Pronouns that Use Singular Verbs