Which word? Tricky words and phrases

  question-mark-question-words-black-39920630Many English words and phrases are commonly confused by native and non-native English speakers alike. This is not hard to understand, given the sometimes-subtle differences between terms. In this post, I discuss some words and phrases that are frequently misused in scientific writing. I will expand on this list in future posts. Do you have a question about word usage? Want to contribute to this collection? Leave a comment below!

Among, between

➛Among expresses relationships involving more than two similar (related) entities with a sense of distribution among the entities. •Photosynthate was allocated among leaves, branches, and fruit. • The abundance of mycorrhizal associations varied among the tree species.

➛Between expresses relationships involving two or more entities, with an emphasis on comparison between pairs (one-to-one). • There were no significant differences in gene expression between any of the treatments. •Their experiment examined the relationship between metabolic rate and interval training.

Associated with, affiliated with

➛Associated is defined as: connected to; joined, united, allied, or combined with; in relationship with. • Many invertebrate taxa were associated with the leaf litter. • The low genetic diversity was associated with geographic isolation.

➛Affiliated is defined as: closely associated with a larger body, group, or organization, often in a dependent or subordinate manner. • The extension office was affiliated with the university’s agronomy department.  • The newly discovered planktonic species were affiliated with phylum Actinobacteria.

Both, each

Both and each have different meanings. Both has a plural sense, and each has a singular sense.

➛Both: one and the other; two together. • The nest was tended by both parents who alternately guarded and fed the young.

➛Each: every one individually or considered one by one. • Each of the systems has advantages and limitations.

  • Consider the sentence: • The experiment was replicated three times for each cultivar. This sentence indicates that there were three replicates of every cultivar used in the experiment. In contrast, if both were used in this sentence: • The experiment was replicated three times for both cultivars, the sentence would suggest that three replicates (total) were used between the cultivars.
Compared to, compared with

➛Compared to is used when the comparison focuses on similarities. • Soil temperature at the forest edge was comparable to that in the savanna.

➛Compared with is used when the focus is on finding similarities or differences in the compared objects. • Compared with conditions during the last survey, sea ice cover was significantly reduced. • Field data were compared with the model output during the validation process.


The word data is a plural noun (the singular is datum), so the parts of speech that modify it should also be plural.

Incorrect: • Clinical data suggests that the isolates acquire echinocandin resistance. Correct: • Clinical data suggest that the isolates acquire echinocandin resistance.

Incorrect: • Our data indicates that the tumors grew by clonal expansion. Correct: • Our data indicate that the tumors grew by clonal expansion.

Incorrect: • The data relies on self-reporting by voluntary participants. Correct: • The data rely on self-reporting by voluntary participants.

Directional words

➛Toward or towards? Upward or upwards? Either usage is technically correct. Merriam-Webster’s Dictionary of English Usage offers this guidance, which I follow when editing: the “ward” version is typically used in American English, and the “wards” form is more commonly used in British English.

• The hatchlings headed toward the ocean… (American English)  • The strategy is oriented towards restoring stream channel morphology (British English)

Impact, affect, effect

Writers often use impact as a synonym for effect (noun, an effect of something) or affect (verb, to affect something). However, impact carries a connotation of force and can suggest a negative effect. Effect and affect are more neutral terms when force is not implied. Here are the definitions:

➛Impact: a forceful coming together; collision; forceful contact; strong influence. The Fukushima nuclear power plant accident had significant impacts on aquatic invertebrates.

➛Effect: a result or consequence of something; an impression produced. Target genes were overexpressed to determine their effects on fertility.

➛Affect: to produce a change in; to act upon or influence. Plant root exudates affected the composition of the microbial community in the rhizosphere.

Other alternatives to impact include: result, consequence, influence, outcome

Intermittent, periodic

The distinction between intermittent and periodic lies in whether the subject occurs regularly or irregularly. Intermittent refers to irregular events; periodic can refer to either regular or irregular events.

➛Intermittent: alternately stopping and starting or functioning and not functioning; occurring at irregular intervals. An intermittent land bridge linked the eastern Palaearctic to the New World. The intermittent stream had been dry for three years.

➛Periodic: recurring at either regular or irregular intervals of time. Oxygen concentrations in the hydroponic solutions were monitored periodically (every 4 h). Although we heard periodic calls, we never saw the Swainson’s thrush.

 Since, because, as

➛Because is used to show a causal relationship. • Because the reagents were volatile, the process occurred quickly.

➛Since and as are used to show temporal relationships. The new instrument arrived just as our samples were ready to be processed. (NOT As we had many samples and our analyzer had broken, we ordered a new instrument.) Sea surface levels have changed significantly since the Pleistocene.

While, although

➛While indicates time. Although suggests conditionality and is synonymous with but and however.

➛While is commonly used to express the meaning although, and it is generally understood in that context. While some wetlands are naturally isolated, human activity is a major contributing factor in wetland isolation.

However, while should not be used in place of although or however when the resulting meaning would be unclear. Consider the sentence While the site was in full sun, the conditions were not ideal for growth. A reader could interpret this sentence to mean that conditions were not ideal when the site was in full sun. This sentence can be clarified by replacing while with although.

  • While is used appropriately in the following sentences: The samples were incubated while the gels were prepared. The low-oxygen environment inhibits aerobic microbial activity while stimulating activity of facultative and obligate anaerobes. Wetland plants take up nutrients, while their hydric soils chemically bind other pollutants.
  • Note that and or but can often be substituted for while: The low-oxygen environment inhibits aerobic microbial activity and stimulates the activity of facultative and obligate anaerobes. • Wetland plants take up nutrients, and their hydric soils chemically bind other pollutants.
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