LOOKING THE PART

After I first published this site, I realized I’d left out something glaringly important: grammar.

…No, wait, come back! I promise this is more relevant (and more interesting) than you think!

Publishing an academic paper means leaving your permanent mark, as a professional, on your field. Every part of your paper—its organization, structure, vision, narrative, figures, prose—should reflect your care and credibility. But for many science writers, one of the easiest places to fall short, especially without training, is with your grammar. That's particularly true for the so-called "intermediate-level" grammar concepts that we're often not explicitly taught and are instead just expected to pick up on via osmosis.

Appropriately or not, I can’t help but judge papers on their grammar. Errors invariably read as signs of inattention to detail, which raises the question: where else were the researchers less attentive? Like a plot hole in a movie, grammar problems can also “take me out of the story”—I start thinking about how the science is being communicated instead of about the science itself. Worse still, some grammar issues obscure meaning entirely.

None of those are the outcomes you want, I assume!

So, this page offers a short, accessible list of the grammar issues I most often see in science writing—especially in the work of students, early-career researchers, and yes, even my own drafts. This isn’t a deep dive into grammar theory; it’s a springboard to help you start to spot some of your common issues...before someone else does. 

COMMAS

In my experience, the single most common class of grammar issues I encounter in scientific writing is those involving commas. Most of these errors stem from misunderstanding the (decidedly medium) strength of a comma as a punctuation mark. Below are the main ways this misunderstanding tends to reveal itself:

1. Using one comma to glue together two complete and equal thoughts.

A comma is not strong enough to hold together two "complete thoughts" (technically called independent clauses). A complete thought is one containing a subject, a verb, and (usually) an object. For instance:

“We performed two separate trials” 

is complete. It has a subject (“We”), verb (“performed”), and object (“trials”). 

But consider this: 

“We performed two separate trials, these occurred two weeks apart.” 

Here, we’ve tried to join two "complete thoughts" with just a comma—what’s known as a comma splice. To fix this, you have a few options. The first of these is to upgrade to a stronger punctiation mark, such as a period, semicolon, or em dash:

“We performed two separate trials; these occurred two weeks apart.”

“We performed two separate trials. These occurred two weeks apart.”

“We performed two separate trials—these occurred two weeks apart.” 

The other option is to add a coordinating conjunction to supplement the strength of your comma:

“We performed two separate trials, but these occurred two weeks apart.”

2. Mixing up your coordinating conjunctions.

Relatedly, there are only seven coordinating conjunctions in English. You can remember them with FANBOYS — for, and, nor, but, or, yet, so. 

So, this sentence doesn’t work:

“We performed two separate trials, however these occurred two weeks apart.”

Why? Because “however” is not a coordinating conjunction. Even paired with a comma, it’s not "strong" enough to do the deed. I recognize this is not instinctively easy to tell!  

3. Separating the subject from its verb with a comma.

The subject and verb of a "complete thought" are a package deal—they should not be separated by a comma. But this happens a lot, especially when the subject is long. For example:

“Our second set of trials comparing the control group to the treatment group, was performed at the same site.”

Here, the comma separates “set” (the actual subject) from “was performed” (the verb), which should make the sentence feel choppy to you. Your brain is still “waiting” for the action, but it's forced to take a "mental pause" at the comma anyway.

To fix this example, we could just remove the comma, or...

4. Not using two commas to form "parentheticals."

Sometimes, we want to set off non-essential info from the main sentence—these are called asides or parentheticals, but you can think of them as "bonus content." We do this "walling off" with a pair of commas.

Let’s revisit our example from above:

“Our second set of trials, comparing the control group to the treatment group, was performed at the same site.” 

With the addition of a comma (rather than a removal), we've "walled off" the sentence's “bonus content," making it clearer to our brain's that the sentence’s spine is “Our set of trials was performed…”. 

We also very frequently place parentheticals at the starts of sentences:

“After the first trial was completed, we started the second.” 

Only one comma is needed here because the “wall” comes before the main clause has even begun. In general, unless introductory elements are adjectives modifying the subject, they should always be walled off from the rest of the sentence with a comma. 

But don’t wall off essential information as though it’s optional. For example:

“After the trial, studying the effects of nitrogen, we performed the other trial.” 

Here, “studying the effects of nitrogen” tells us which trial we’re even talking about—the reader will be lost without this info. So, the first comma should be removed in that case (but we still need the second—can you explain why now?)

5. Omitting commas in lists of three or more items 

Use commas to separate items in lists of three or more: 

“The trials studied the effects of nitrogen timing, varied soil texture, and predation pressure.” 

Each comma helps separate ideas into distinct “bins,” which your reader’s brain appreciates—especially when the list itself is long, the items in it are long, or both (as was kind of the case here!). 

The Oxford comma (before the final “and”) is optional according to some, but it’s never wrong, and it can prevent ambiguity, so I recommend you always include it.

By contrast, never use a comma between just two co-equal items: 

“Nitrogen, and soil texture were varied as follows.” 

Hopefully, that example just reads as straight-up weird to you!

PARALLELISM

Parallelism occurs when two or more items are grammatically linked, usually using a coordinating conjunction like “and” or “or.” Another way to put it: we’re building a list—whether it’s two items or twenty—and we want the reader to recognize that the items in it are not just grammatically, but also meaningfully, equivalent.

Take this sentence:

“The trials studied the effects of nitrogen timing, varied soil texture, and predation pressure.” 

That works! It communicates a list of our three co-equal study aims. It's when we've created false equality—or when the grammar breaks down for one or more list items—that we get in trouble. Here are four common ways that happens: 

1. When the grammar doesn’t work for all list items.

A great way to test your lists for faulty parallelism is to temporarily remove all but one item in turn and check to see if the sentence still makes sense for each one on its own. Here’s a sentence that fails that test: 

"We randomly subsampled our plots either a quarter-hour, half-hour, or hour after applying the treatment." 

Can you spot the issue? Here, if you try the trick here, "...subsampled our plots...a hour..." doesn't work. That should be "an hour," right? 

In this case, we either need to somehow rephrase the sentence to avoid the mismatching articles altogether:

"We randomly subsampled our plots either 15, 30, or 60 minutes after applying the treatment." 

Or else distribute the proper article down into each list item:

"We randomly subsampled our plots either a quarter-hour, a half-hour, or an hour after applying the treatment." 

This latter option works but, if you go this route, be sure to include the article in every item. This would seem inconsistent at best:

"We randomly subsampled our plots either a quarter-hour, half-hour, or an hour after applying the treatment." 

This kind of issue also comes up with prepositions and modifiers like adverbs too. 

2. When the list items differ in grammatical form.

Parallel items should have parallel structure. Consider: 

"We made sure to handle trapped animals carefully, gently, and with caution."

The first two items (carefully, gently) are adverbs. The third (with caution) is a prepositional phrase. It’s not exactly ungrammatical, but the mismatch in form feels awkward.

In this case, we can fix this simply by replacing "with caution" with the equally understandable adverb "cautiously." As a bonus, it's one word shorter! Clever parallelism often is. 

3. When the subjects/objects change mid-list.

This one’s sneakier. Every item in a list should share the same implied relationship to the subject and/or verb. But it’s easy to lose track of those relationships when lists get long: 

Consider this sentence:

“We monitored weekly insect predation rates, identified trapped organisms to the species level, and traps were cleaned each month."

In the first two list items, “we” is the subject. But, suddenly, in the third, “traps” becomes the subject, and we even get a new verb "were" too. That’s a parallelism fail. 

There are two ways to fix this. First, we could correct the third list item so it matches the subject of the first two:

“We monitored weekly insect predation rates, identified trapped organisms to the species level, and cleaned traps each month."

Or, if we prefer, we could shift to putting just the first two items in parallel and treat the third as a new, independent thought:

“We monitored weekly insect predation rates and identified trapped organisms to the species level, and traps were cleaned each month."

Now both subjects are clear and consistent within their respective clauses. 

4. When the list items aren't equal in meaning.

Even when the grammar checks out, parallelism can still break down semantically. That is, you may accidentally imply that things are equivalent in meaning or status when they’re not. Take this example:

“We hauled sample kits, safety gear, and undergraduate students to the study site each day."

Is this grammatically correct? Yup. Does it also make it sound like your undergrads are just another piece of field equipment? Yup. We should not be "hauling" our undergrads around like we do "gear!" 

Parallel structures send implicit messages about the relationships between things. Be careful about what kinds of messages you're sending this way!

NEEDLESS WORDS

Good grammar is ultimately about clarity. Even if a sentence is technically correct, too many words can obscure your message. That’s why one of the best ways to improve your writing—especially during revision—is to trim needless words, those that add nothing but length.

Let’s walk through a few of the usual suspects:

1. "That". 

About 15% of the time, “that” is essential. For example: 

"The study plot that failed to receive the treatment was excluded." 

Here, “that failed to receive the treatment” tells us which plot we're talking about. You can tell "that" is essential here because removing it breaks the grammar of the sentence.

But the other 85% of the time? “That” is dead weight. Take this sentence: 

"The hypothesis that we tested pertained to nitrogen limitation."

Try removing "that" from the sentence:

"The hypothesis we tested pertained to nitrogen limitation."

Did the meaning change or become any less clear? Nope! 

My advice? When editing, try removing every “that.” You might be surprised how many you don’t need!

2. "Of".

“Of” in a preposition, so it can begin prepositional phrases—structures like “the edge of the plate” or “the results of the experiment.” Sometimes, these are fine. But, often, they’re needlessly long. Take this example:

"The system of logic we used has been supposed by previous research."

In this case, we had an alternative: We could simply have used an adjective directly, such as: 

"The logical system we used has been supposed by previous research."

Another option we frequently have is to use a possessive. Take:

"The shoreline of the lake was complex."

This could be substituted for:

"The lake's shoreline was complex."

My advice: When you see “of,” ask if a possessive (‘s) or a single adjective could do the same job. Again, try deleting every "of" phrase you encounter to see if you can replace it.

3. Phrasal verbs.

You ever notice that English has a lot of "multi-word" verbs? "Screw on," "move over," and "pull in" are some examples, each meaning something different than "screw in," "move on," or "pull over." 

Sometimes with these, every word matters. Other times, the extra bits add nothing. Consider:

"We trimmed up our study plants to prevent them from blowing over."

The “up” adds no meaning here. “Over,” on the other hand, is essential—“blowing over” is not the same as just “blowing.”

My advice: Don’t assume every verb needs any second words. Ask if just the verb alone get the job done.

4. Circumlocutions. 

Big word, simple idea. Circumlocutions are multi-word phrases that could be replaced with just 1-2 words. Some examples include: 

• “in order to” → “to”

• “due to the fact that” → “because”

• “a variety of” → “many”

• “make an appearance in” → “appear in”

These phrases tend to show up in first drafts, when we’re still “talking to ourselves." That’s normal. But, during revision, it’s worth hunting them down.

SCIENCE PECULIARITIES

There are a few grammatical quirks that show up far more often in scientific writing than in everyday prose. Here's a rundown of some common ones: 

1. i.e., and e.g., (and Latinisms in general)

“i.e.” stands for id est (“that is”), and introduces a clarification. “e.g.” stands for exempli gratia (“for example”), and precedes one or more examples. These are not interchangeable, nor should they be used in the same sentence.

Both are generally followed by a comma. You can italicize them (like you would foreign phrases generally) but, because they are quite common, you no longer need to. If you begin a sentence with either, just the first letter is capitalized. 

"We studied pollinators (e.g., bees, hoverflies, and butterflies), all of which may respond differently to landscape change."

2. Unusual plurals

Scientific writing uses a number of Latin- or Greek-derived plurals you'll probably want to memorize. Some common ones include: taxa (singular: taxon), data (datum), genus (genera), criteria (criterion), and phenomena (phenomenon). Yes, "data" is plural! This is admittedly changing, as the language evolves, but “The data were analyzed…” is still safest.

3. Math symbols

Whenever you write any "in-line" math including symbols like =, <, or +, there should be a space on either side. In general, the whole equation should be punctuated like regular text. Using an actual multiplication symbol (×) is best.

4. Units

Whenever you provide a value plus a unit, put a space between the two, such as in "5 meters." This applies even when we abbreviate the unit, as we usually do, such as in "5 m." There are, however, a few exceptions like degrees and percents where no space is used.

5. Multiple-word adjectives

...You see what I did there?? Whenever you use 2+ words as a single adjective to modify a single noun, the words in that multi-part adjective usually need to be hyphenated together:

"We used state-of-the-art methods."

Oddly, you don't need to do this when the adjective comes after the noun, though:

"Our methods were state of the art."

You also needn't use the hyphen when the earlier word ends in -ly:

"Our systematically sampled plots were distributed across five acres."

If you have several multi-word adjectives in a row, you may omit the leading word but not the hyphen in the second, such as in:

"Our air-filtered and -dried samples were taken back to the lab."