A Subject We Can All Agree On

cartoon of girl at computer with thought bubble about subject verb agreement

‘The data was analyzed.’ Or is it ‘The data were analyzed’?

Science does involve a fair amount of analysis but often not of grammar rules. But both of the above sentences sound correct, so how do you know which sentence is grammatically correct? The grammatical error in question is that of subjectverb agreement. Technical writing is plagued by incorrect subject-verb agreement, and you want your data, not your confusing sentences, to stand out! After a brief lesson on sentence structure and a few simple rules, you’ll be back to focusing on data analysis and less on grammar!

Sentences are structured with a subject and a predicate. The subject refers to the part of a sentence that contains the person, place, thing, or idea that is doing something or being something. This person, place, thing, or idea is the noun. The predicate is the part of the sentence that includes the verb, or what the subject is doing or being.

And subjects (or nouns) and verbs must agree! That is, subjects and verbs can be singular or plural, and a few simple rules govern how subjects and verbs match within a sentence.

Following the first rule of subject-verb agreement often is enough to put your grammar questions to rest.

RULE 1:  A singular subject has a singular verb.  Plural subjects have plural verbs.

The gene variant causes increased risk for disease.

Variant is the noun and causes is the verb. There is only one variant, so the noun is singular. Therefore, the verb must also be singular.

The cells proliferate under constant temperature.

Cells is the noun and proliferate is the verb. We’re talking about more than one cell, so the noun is plural and must take a plural verb.

HELPFUL HINT: If you’re confused by what verb form to use, try replacing the subject with a word that you know to be singular (e.g., study, cell, or patient) or plural (e.g., studies, cells, or patients). Then choose the verb form to match.


When sentences are simple, the subject and verb are easy to identify. However, scientific writing isn’t always simple, making subject-verb disagreement a common mistake. For example:

Following the incubation period, the patient-derived cell lines, termed LNP-a and LNP-b, were transfected with plasmid DNA and grown to confluency in a 10 cm dish under constant temperature.

This example contains more information and may be more typical of the types of technical writing scientists produce. Unfortunately, the sentence also has more words. Here, a second rule for subject-verb agreement applies.

RULE 2:  The subject is not affected by phrases that are between the subject and verb.

In the above example, strip away all the “extra” information and find the most basic sentence possible that still makes sense.

Following the incubation period, the patient-derived cell lines, termed LNP-a and LNP-b, were transfected with plasmid DNA and grown to confluency in a 10 cm dish under constant temperature.

The cell lines were transfected.

✅The noun lines or cell lines (plural) agrees with the verb were transfected (plural).


In most cases, Rules 1 and 2 will suffice. However, keep an eye out for the following complexities:

Compound subjects, collective nouns, and indefinite pronouns

Compound subjects are subjects that are connected by “and, “or, or other phrases. Use of a singular or plural verb will depend on how the subjects are connected.

  • Two or more items in a subject connected by and” use plural verbs (unless the words refer to the same thing).

    Western blot and immunohistochemistry were performed for all samples.

    ✅A western blot and immunohistochemistry are two different procedures. When combined by “and”, the verb will take a plural form.

    Environmental health and safety mandates that all biosafety cabinets be certified annually.

    ✅Environmental health and safety is one group and, therefore, takes a singular verb.

    • Two or more items in a subject connected by “or”, “either…or”, “neither…nor”, or “not only…but also” use singular verbs. If the two items in a subject are plural, a plural verb is used. If one of the items is singular and the other plural, then the verb agrees with the nearest noun.

    The glutamate agonist or GABA inhibitor induces neuronal activity.

    ✅Both the noun agonist and noun inhibitor are singular; therefore, the verb induces is singular.

    Glutamate agonists or GABA inhibitors induce neuronal activity.

    Agonists and inhibitors are now plural so the verb is also plural.

    An altered sleep cycle or other stressors disrupt normal mouse behavior.

    ✅Both cycle and stressors are the nouns, but one is singular and the other plural. The noun stressors (plural) is closest to the verb disrupt (plural).

    Collective nouns are used to refer to an entire group of people. The verb forms collective nouns use depend on whether the collective noun is acting as one unit (singular) or as separate individuals (plural). Collective nouns that may be found in scientific writing include assembly, group, staff, or team.

    The team of researchers has identified a common genetic cause for preterm births.

    ✅The team is acting as one unit and takes a singular verb.

    The team of researchers disagree about the genetic cause for preterm births.

    ✅Each member of the team has a different opinion and are now acting as separate individuals, so a plural verb disagree is used.

    Indefinite pronouns are nouns that do not identify a specific person, place, or thing. Indefinite pronouns include both, several, all, each, none, neither, or either. The table below can be a quick reference to identify the verb forms for commonly used indefinite pronouns. Some indefinite pronouns may vary in their verb agreement, depending on the context. In these cases, choose the verb based on the actual noun the pronouns refer to.

    Both of the culture dishes were contaminated by the bacteria.

    Each of the culture dishes was contaminated by the bacteria.

    All of the cultures dishes were contaminated by the bacteria.

    None of the culture dishes were contaminated by the bacteria.

    NounVerb Form
    Both, few, many, others, severalPlural
    Another, anybody, anyone, anything, everybody, everyone, everything, little, many a, more than one, much, otherSingular
    All, any, each, more, most, none, plenty, some, suchSingular or plural


    (see examples above)

    None (as in no one, nobody, nothing)Singular
    None (as in no two or no amount)Plural
    Each (as in each one)Singular
    Neither, either (when used by themselves in a sentence)Singular


    Percentages or fractions

    Twenty percent of the dish is composed of cells.

    Ten percent of the neurons were stained green.

    The nouns twenty percent and ten percent are not used to determine the verb form. Instead, the words between the noun and verb are important. In these cases, correct subject-verb agreement is actually an exception to Rule 2.

    When referring to a fraction or percentage of a singular item (e.g., dish), the verb is also singular. Likewise, a fraction or percentage of a plural item (e.g., neurons) takes a plural verb.


    Statistics, criteria, data, media, number, and total

    Are these nouns singular or plural? Science does contain a few tricky nouns, and it’s difficult to determine whether they are singular or plural. To help you get started, a few common examples are explained below.

    • Statistics can take a singular or plural verb depending on the context.

    Statistics is a class required by all incoming graduate students.

    ✅In this example, statistics is referring to one (singular) class that graduate students must take. The verb must also be singular.

    The statistics indicate that expression of gene X positively correlates with tumor cell growth.

    ✅Here, statistics is referring to multiple tests (plural) that were done to determine a correlation. The verb must also be plural.

    • Criteria, data, and media are all plural nouns and require a plural verb. Criterion, datum, and medium are their singular counterparts (although not often used).
    • If using “number” or “total” as the noun, the verb form depends on whether you say “the number/total” or “a number/total”.

      The number of platelets was greater in the control group compared to the treatment group.

      A number of platelets were seen infiltrating the connective tissue.

      If you’re still unsure whether a tricky noun is singular or plural, take a look at the literature in your field. How do other authors use that particular noun in a sentence?


      Let’s think back to our original example:  The data was/were analyzed.  Which do you think is the correct verb?

      Good luck with your analyses – data and grammar alike!


      Brooks, B.S., Pinson, J.L., and Wilson, J.G. (2010). Working with Words. Boston, MA: Bedford/St. Martin’s.

      American Medical Writer’s Association. Basic Grammar and Usage. Subject-Verb Agreement, Chapter 6.