Common Mistakes with the Plural of Datum
If you are writing about a single piece of information, the correct word is datum. When you have more than one piece, the standard plural is data. However, many writers make mistakes because data is often treated as a singular mass noun in everyday English, even though it is technically plural. This guide explains the difference, shows you when to use each form, and helps you avoid common errors in medical, academic, and professional writing.
Quick Answer: Datum vs. Data
| Word | Number | Example |
|---|---|---|
| Datum | Singular | This datum supports the diagnosis. |
| Data | Plural (traditional) | These data show a clear trend. |
| Data | Singular (informal/common) | The data is ready for review. |
In formal medical and scientific writing, use datum for one item and data as a plural noun with plural verbs (e.g., the data are). In everyday conversation and less formal writing, data as a singular mass noun is widely accepted.
Understanding Datum and Data
Datum comes from Latin and means a single piece of information, measurement, or observation. In medical contexts, a datum could be one lab result, one patient reading, or one survey response. Data is the plural form, meaning multiple pieces of information.
Many English learners struggle because data is used so often as a singular noun that it sounds strange to say the data are. However, in formal medical reports, research papers, and academic journals, the plural treatment is still preferred.
Formal vs. Informal Tone
In a formal medical article or research paper, you should write:
- Correct: The data were collected over six months.
- Correct: Each datum was verified by a second technician.
In an email to a colleague or in everyday conversation, you can write:
- Acceptable: The data is ready for the meeting.
- Acceptable: Can you check this datum before we present?
The key is to match your audience. If you are writing for a medical journal, use the traditional plural. If you are texting a coworker, singular data is fine.
Comparison Table: Datum vs. Data
| Context | Singular Form | Plural Form | Example Sentence |
|---|---|---|---|
| Medical research paper | Datum | Data (plural verb) | The datum from this patient is unusual. The data from all patients are consistent. |
| Clinical report | Datum | Data (plural verb) | Each datum was recorded separately. The data indicate a need for further testing. |
| Email to a colleague | Datum (rare) | Data (singular verb) | The data is in the shared folder. Can you check this datum? |
| Everyday conversation | Datum (rare) | Data (singular verb) | The data looks good. I need one more datum to finish. |
Natural Examples
Here are examples that show how datum and data are used in real medical and professional situations.
Example 1: Research Context
We collected one datum from each participant at baseline. After six weeks, we gathered additional data. The data were analyzed using a paired t-test.
Example 2: Clinical Setting
The nurse recorded a single datum for blood pressure. Later, the doctor reviewed all the data from the shift. The data suggest the patient is stable.
Example 3: Email Communication
Hi Dr. Chen, I have attached the datum for patient 102. The rest of the data is in the main report. Please let me know if you need anything else.
Example 4: Everyday Conversation
I only need one more datum to complete the chart. After that, the data is ready for the presentation.
Common Mistakes
Here are the most frequent errors learners make with datum and data.
Mistake 1: Using Data as a Singular in Formal Writing
Incorrect: The data is conclusive. (in a research paper)
Correct: The data are conclusive.
Mistake 2: Using Datum as a Plural
Incorrect: We have several datum to review.
Correct: We have several data to review.
Mistake 3: Forgetting Datum Exists
Many learners only know data and never use datum. In formal writing, using datum for a single item shows precision.
Mistake 4: Mixing Singular and Plural Verbs
Incorrect: The data is collected, and then they are analyzed. (mixing singular and plural)
Correct: The data are collected, and then they are analyzed.
Better Alternatives and When to Use Them
If you are unsure whether to use datum or data, consider these alternatives:
- For a single item: Use datum, measurement, observation, result, or value. Example: This measurement is important.
- For multiple items: Use data (plural verb in formal writing), results, findings, or information (singular). Example: The findings were published.
- When in doubt: Use information as a singular mass noun. It is always safe. Example: The information is accurate.
When to Use Datum
Use datum when you want to emphasize that you are talking about one specific piece of data. This is most common in formal medical writing, research methods sections, and technical documentation.
When to Use Data as Plural
Use data with a plural verb in academic papers, medical journals, and formal reports. This shows that you understand the traditional grammar rule.
When to Use Data as Singular
Use data with a singular verb in emails, casual conversation, and informal writing. This is widely accepted and sounds natural to most native speakers.
Mini Practice: Test Your Understanding
Choose the correct word for each sentence. Answers are below.
- This (datum / data) needs to be verified before we proceed.
- The (datum / data) from the study (is / are) published in the journal.
- We collected one (datum / data) from each patient.
- All the (datum / data) (was / were) reviewed by the ethics committee.
Answers
- datum (singular, one piece of information)
- data and are (formal plural treatment)
- datum (one item)
- data and were (formal plural treatment)
Frequently Asked Questions
1. Is it ever correct to say “a data”?
No. Data is either plural or a mass noun. You should not say a data. Instead, say a datum or a piece of data.
2. Can I use “data” as a singular in a medical journal?
Most medical journals still prefer data as a plural noun. Check the journal’s style guide. If you are unsure, use the plural form to be safe.
3. What is the plural of “datum” in Latin?
The Latin plural is data. English borrowed this form, so we use data as the plural in English as well.
4. Is “datums” a word?
Yes, but it is rare. Datums is used in surveying and engineering to refer to multiple reference points or coordinate systems. In medical writing, stick with data for the plural.
Final Tips for Medical Writers
When you write about medical information, remember these three rules:
- Use datum for one item in formal writing.
- Use data with a plural verb in formal contexts.
- Use data with a singular verb in informal contexts.
If you follow these guidelines, you will avoid the most common mistakes. For more help with medical plurals, explore our Confusing Plurals section or check our FAQ for additional questions. You can also read our Editorial Policy to understand how we create these guides.
