Scientific Writing Grammar Mistakes to Avoid

A well-written manuscript communicates your science. A poorly written one gets flagged before a reviewer reads a single finding. Research published in PLOS Biology found that 38% of non-native English speaking researchers have faced paper rejection due to English writing problems alone. With 98% of scientific publications written in English, that is a significant barrier facing most of the world’s researchers. This blog covers the most common scientific writing grammar mistakes, explains where they show up across your manuscript, and shows you exactly how to fix them.

Are Your Verb Tenses Correct Across Every Paper Section?

Each section of a research paper uses a different tense. Methods and results use past tense because they describe what you did. “We incubated the samples for 24 hours” and “The treatment group showed a 30% improvement” are both correct. The introduction and discussion use present tense for things that are already known in science. “Inflammation plays a key role in tissue damage” is a statement about accepted science, not a past event.

The most common mistake happens in the discussion section. Writers slip into past tense after spending weeks in it. A sentence like “The data indicated that the compound was effective at reducing inflammation” makes a known fact sound like a one-time finding. The correct version reads “The data indicate that the compound is effective at reducing inflammation.” That small change matters to reviewers.

When “A” and “The” Change the Meaning of a Research Claim

For researchers writing in a second language, articles are one of the most persistent grammar mistakes in scientific writing. “A catalyst increases reaction speed” is a general statement about a class of compounds. “The catalyst increases reaction speed” refers to the specific one in your study. Using the wrong article creates confusion about whether you are reporting your own finding or describing something already known in the field.

This mistake is especially common among researchers from Japan, China, Korea, and the Arab world, where native languages do not use articles. Article errors are regularly flagged in peer review feedback from these regions, and they are easy to miss when you are reading your own writing.

What Is a Dangling Modifier and Why Do Methods Sections Have So Many?

A dangling modifier is a phrase that does not connect clearly to the right subject in a sentence. In scientific writing, this can make your methods read as though the equipment performed the action, not you.

Here is a common example: “Using gel electrophoresis, the protein bands were clearly visible.” The phrase “using gel electrophoresis” is supposed to describe what the researcher did. But it ends up describing “the protein bands,” which makes no sense. The correct version reads “Using gel electrophoresis, we observed clearly visible protein bands.” Trinka’s grammar checker catches these errors in research paper contexts. General writing tools often miss them because they are not built for scientific writing.

Are Vague Pronouns Weakening Your Discussion Section?

Words like “this,” “it,” “these,” and “they” are easy to overuse in the discussion section. The problem arises when they refer back to a previous idea without making it clear which one.

“The experiment showed increased cell viability. This was consistent with previous studies.” What exactly was consistent? The result? The method? The reader has to guess. Replace the vague word with the specific noun. “This increased cell viability was consistent with previous studies” is clear and direct. Go through your discussion and stop at every “this” and “it.” If you are not sure what it refers to, your reader will not be either.

Noun Strings That Slow Every Reader Down

A noun string is when three or more nouns are placed together as a description. It forces readers to figure out what the phrase means before they can move on.

“Protein expression level measurement protocol” puts four nouns in a row. Try “protocol for measuring protein expression levels” instead. It says the same thing but is much easier to read. This matters especially for ESL researchers and readers from other disciplines. Keeping modifiers to two nouns at most is a simple habit that makes a real difference to readability.

Getting It Right Before the Reviewer Does

Grammar mistakes in scientific manuscripts rarely come from carelessness. They come from writing under pressure, working in a second language, and following rules that nobody formally teaches. The five errors covered here are all fixable once you know what to look for.

Before your next submission, check your manuscript with Trinka grammar checker. It is built for academic and scientific writing, which means it catches tense errors by section, article mistakes, modifier issues, and other patterns that general tools are not trained to recognize.