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Writing in English for Non-Native Authors

The problem

“Journal editors, overloaded with quality manuscripts, may make decisions on manuscripts based on formal criteria, like grammar or spelling. Don't get rejected for avoidable mistakes; make sure your manuscript looks perfect” (quote from a senior executive at a large international publishing house).

Scientific writing is difficult enough for many authors who have English as their first language; for non-native English-speaking authors, writing a paper in English represents a massive challenge that can make or break their paper’s chances of publication.

With increased pressure on publication space and increased demands on editors’ time many journals are introducing language screening protocols to check submissions before they reach the editor’s desk. Some editors simply choose to overlook papers that are too poorly written. However, all is not lost for non-native English-speaking authors: by being aware of some of the most common scientific writing language errors and how to avoid them, you can improve the quality of your paper and increase its chances of being accepted.

The solution

It is helpful to think of the writing process in the same way that you think about performing experiments. The language needs to be easily and accurately understood by the reader without multiple possible interpretations arising. In experiments, we use controls to rule out alternative hypotheses. In language, we must avoid ambiguities and unnecessary text to get our message across clearly.

Scientific writing should possess what I call the "three C's": clarity, conciseness and correctness (accuracy). The key to achieving this is to be as brief and specific as possible without omitting any details that might be essential for the reader to fully understand your meaning. In other words, say no more than you need to accurately convey your message.

Although writing that fails to meet this standard is sometimes described as “sloppy” or “lazy” writing, authors are frequently unaware that what they have written is unclear and ambiguous. Thus, attention to detail and an appreciation of how your writing could be misinterpreted are essential. What follows is just a small selection of error types that, when present in large numbers, could result in your paper going straight to the ‘rejected’ pile.

Articles (a, an, the) are adjectives that modify nouns. If they are used incorrectly the reader can be left wondering if you are referring to a specific thing or to a non-specific item or category. Worse, they could interpret the text incorrectly and make a wrong assumption. Incorrect use of articles can also lead to confusion relating to singular vs. plural senses.

Which article?

The word “the” should be used in conjunction with a noun referring to a particular item or group of items (it can be used with both plural and singular nouns). For example, “the sections were then stained with H&E” implies that the sections you had referred to in recent sentences were stained. By contrast, “a” should be used in conjunction with non-specific nouns. For example, “a section was then stained” infers that a single section, any section, was stained. “A” should only be used to refer to a single item or category, and should not be used in conjunction with plural nouns. So saying “a sections” would be incorrect.

Asian authors frequently leave articles out of sentences making them sound awkward and unnatural, which would be the case when omitting the “the” in “adenovirus was injected into the fourth ventricle.”


  • “The antibody was injected into the hippocampus…” (articles required to specify a particular antibody, presumably already referred to in the text, and a specific hippocampus, belonging to a subject already described).
  • “A new method of extraction was devised…” (“a” used rather than “the” because this statement introduces this method to the reader, therefore it is non-specific at that time. Once introduced to the reader, “the new method of extraction” should be used to refer to that method in the specific sense).

Singular or plural?

Nouns are used in the plural sense by adding an “s” to the end (in most cases). In the absence of an article, it can sometimes be unclear if the wrong sense (plural vs. singular) has been used. For example, in the sentence “Acetyl group was added,” the reader is not clear whether the author means “An acetyl group was added,” or perhaps “Acetyl groups were added.”

Thus, when referring to multiple items, the plural sense should be used to avoid potential confusion. This is commonly forgotten when describing figures (use “arrowheads” rather than “arrowhead” where there is more than one in the figure; likewise, use “solid bars” rather than “solid bar” when referring to a bar chart with multiple bars).


  • “A biopsy was obtained…” (describing a single biopsy).
  • “Biopsies were obtained from eight patients…” (no article necessary unless these biopsies had already been introduced to the reader, in which case they would need to be referred to in the specific sense “The biopsies were obtained…”).

Used incorrectly, these three elements of writing can introduce ambiguities, and the potential for subsequent misunderstanding, into your writing.

Using commas and hyphens

In the sentence "Because Aβ42 levels were elevated in 75% of AD patients in studies using our method [6,7], it is critical to obtain fresh samples," moving the comma after method to follow the word “patients” (or addition of a new comma there) would completely change the meaning.

Similarly, in the phrase “calcium-induced calcium release,” omission of the hyphen completely changes the meaning of the sentence. When the hyphen is present, "calcium-induced" is a compound adjective modifying the noun "calcium release." When the hyphen is absent, "induced" is a verb describing the effect of calcium on calcium release. Thus, it is critically important to use hyphens with such compound adjectives to avoid misunderstandings. However, no hyphen is required to combine an adverb and an adjective. For example "highly intense staining" and "high-intensity staining" are both correct, but "highly-intense staining" is not.


  • "Glutamate receptors mediated synaptic plasticity..." tells the reader that Glu receptors are involved in the development of synaptic plasticity.
  • "Glutamate receptor-mediated synaptic plasticity..." identifies synaptic plasticity involving Glu receptors as the subject of the sentence (note the change from plural to singular because "receptor" is being used in a general sense and not to refer to a single receptor).

Using "which"

The word "which," when used incorrectly, can also induce considerable confusion. It is often confused with the word "that." Both introduce clauses that modify nouns, but "that" should be used to introduce defining or restrictive clauses and "which" should be used to introduce non-defining or non-restrictive clauses.

For example, in "the sections that were positive for GFP were subjected to cell counting procedures," the "that" introduces a defining clause that defines exactly which sections were subjected to cell counting. By contrast, in "the sections, which were positive for GFP, were subjected to cell counting procedures," the sections that were subjected to cell counting are rather loosely defined, possibly referring to sections that have been described in the previous or recent sentences. The clause about GFP positivity provides the reader with additional information, but is not essential to understand the meaning of the sentence.

Because "which" is used in this way, writers need to ensure that it is absolutely clear what the "which" is actually referring to. This could possibly be whatever immediately precedes it (most common), or possibly the main subject of the sentence. For example, the sentence "microglia migrated to the site of the lesion, which was associated with increased levels of ED-1" is somewhat vague, because it is unclear if the "which" is referring to the lesion or to the migration of microglia.

If there is ever any doubt about such a sentence, it is best to rephrase it completely. To avoid ambiguity, the sentence about microglia could be re-written as "migration of microglia to the site of the lesion was associated with increased levels of ED-1" or "microglia migrated to the site of the lesion, and immunohistochemical analysis revealed increased levels of ED-1 at this site."


  • "Data were normalised to the housekeeping gene actin, which was used as an internal reference..." Here the "which" refers to actin, which is therefore the subject of the following clause.
  • "Data were normalised to the internal reference housekeeping gene actin, revealing increases in the levels of..." To refer to the analyzed data in a subsequent clause, "which" would be inappropriate and introduce an ambiguity.

The word "respectively" is frequently misused by native and non-native English-speaking authors alike, and, as with the other elements described above, its misuse can lead to confusion and ambiguities. It is often clearer not to use this term at all, but it can be useful to economize on words where there are two corresponding lists.

Respectively is quite useful in the sentence “The latencies to withdrawal from a painful stimulus in control and transgenic mice were 3 s and 2 s, respectively,” meaning that control mice withdrew after 3 s and transgenic mice withdrew after 2 s.

When describing something much shorter than “The latencies to withdrawal from a painful stimulus,” such as average weights, respectively is not necessary. “Control mice weighed 20±3 g and transgenic mice weighed 17±2 g” is better than “Control mice and transgenic mice weighed 20±3 g and 17±2 g, respectively,” which contains one additional word.

Note that “respectively” can only be used to refer to two corresponding lists at one time, and cannot be used to refer to more. Thus the sentence “The latencies to withdrawal from 5 g and 10 g painful stimuli in control and transgenic mice were 3 s and 2 s, respectively” is incorrect and impossible to understand.


  • “The proportions of monocytes positive for CD163, CD7 and CD11a were 45%, 63% and 70%, respectively.” In this sentence, the “respectively” makes clear that the three percentages refer to each of the three markers in the same order.

Comparisons are frequently made in the results sections of papers, and it is especially important to compare "like with like."

One common error made by non-native authors is overlooking this simple rule and leaving the reader to make an assumption about what is being compared. At best, the language will appear unnatural but the meaning clear; at worst, the wrong meaning can be imparted. As an example, the sentence "Expression levels of p53 in smokers were compared with non-smokers" should actually be "Expression levels of p53 in smokers were compared with those in non-smokers."

Another frequent error with comparisons is the use of relative terms (higher, greater, more, etc.) without a reference. In the sentence "transgenic mice showed higher levels of cortisol" it is unclear what these levels were higher than. Thus, a "than clause," such as "than control mice," is required. The reader might make this assumption automatically, but in some cases alternative inferences will be possible, and the goal of accurate scientific writing has to be the removal of all assumption. Because comparisons of results are critical to their interpretation and, ultimately, their significance, it is critical that you convey to the reader exactly what is being compared.

Finally, the word "between" should be used for comparisons of two findings, but "among" should be used for comparisons of three or more.


  • "The levels of ubiquitinated proteins were higher in patients than in control subjects." In this sentence, the "than clause" provides a reference for the term "higher."
  • "The levels of ubiquitinated proteins in patients were higher than those in control subjects." Unlike the first example, where patients and controls are both on the same side of the comparing term, that is, they are both mentioned after "higher," here, patients and controls appear either side of the comparing term. Therefore, it is necessary to add "than those" to compare like with like.
  • "There was no significant difference in the levels of ubiquitinated proteins between patients and controls." The word "between" is appropriate here for a comparison of two groups.
  • "There were no significant differences in the levels of ubiquitinated proteins among AD patients, PD patients and controls." The word "among" is appropriate for comparisons of more than two groups (note the change to the plural differences because more than one type of difference is possible with more than two groups).

One very common cause of confusion is use of the incorrect nomenclature to describe changes in the levels of genes, their mRNAs or the proteins that they encode. Constant changing from describing gene expression levels to protein levels and back again can also add to the confusion, especially because the names are often the same. Therefore, it needs to be completely clear to the reader exactly what level you are talking about.

Using proper nomenclature
Nomenclature differs among species, but generally gene names should be described in italics and protein names in normal font. Case (upper vs. lower) is often used to distinguish between species: generally, for mouse, rat and chicken, gene names are spelled with an upper case first letter and the rest in lower case; for humans, primates and some domestic species, gene names are spelled with all capital letters.

Descriptions of mRNAs generally use the gene name (levels of p53 mRNA), or you can refer to the mRNA "for" a given protein (levels of the mRNA for p53). The word "expression" is usually used to describe gene expression and can induce confusion when used to describe protein and mRNA levels. In most cases when referring to proteins, the word "expression" can simply be replaced with the word "level" (or "levels").

Be aware of the correct nomenclature for your species of subject and ensure that everywhere you refer to a protein, gene or mRNA by name in the text it is completely clear which of those you are referring to.


  • "Expression of the Igf1 gene was increased in our transgenic mice." The use of italics and the word "gene" ensure that no confusion is possible here.
  • "The levels of IGF1 mRNA were elevated in our patient group." This sentence uses correct nomenclature for human genes.
  • "The serum IGF1 levels were elevated in the transgenic mice." Here, it is clear that the protein is being referred to. Capitals are appropriate in this case, even though the species is mouse, because it is the correct nomenclature for the mouse protein.

These are just a few of the most common errors made by non-native English-speaking authors in their scientific writing. There are of course many more that can’t be dealt with here, but they all have the same result: a loss of clarity and/or introduction of ambiguity.

Keep the following points in mind to automatically improve the chance of getting your study published:

  • Apply the 3 C's (clear, concise, correct)
  • Remove repitition and redundancy
  • Be attentive to detail to ensure your meaning is clearly conveyed in each sentence
  • Keep sentences short and simple

The slogan for the Beijing Olympics was "One world, One dream;" when it comes to scientific writing you should think "One sentence, One idea." The simplest solution is always the best.