My quest against 'respectively'

I hate the word “respectively”. So much so, that I have students come back, years later, and tell me that they wrote “respectively”, thought of me, and deleted it. I consider this a mark of good teaching.

What we should embrace in our writing, above all, is clarity.

But why do I hate “respectively”? It is a perfectly good word, useful when one wants to say that something happened to party A and something else happened to party B, but in a lot less words. And if we are advocating for conciseness, shouldn’t we embrace those words that help us say more with less?

Here is my problem with “respectively”. When used carelessly, it may cause confusion and might force people to re-read our sentence. And really, what we should embrace in our writing, above all, is clarity.

There is no problem when “respectively” is used with two items. I can say that Simon and Garfunkel are reading Emily Dickinson and Robert Frost, respectively, and it is easy to tell who is reading whom. Even with three people, the meaning is still clear: Peter, Paul, and Mary are eating tacos, samosas, and falafel, respectively, and everyone knows who is having what.

More than three items, however, will make your sentence unwieldy. If I say that John, Paul, George, and Ringo are reading, writing, walking, and jumping, you may have a harder time recalling what each person is doing. It’s even worse if I use technical terms, such as saying that the new observatory has hygrometers, anemometers, barometers, and thermometers to measure humidity, wind speed, pressure, and temperature, respectively. At this point one may as well reconsider the use of technical terms altogether and save our reader the etymology lesson.

There are worse offenses, like mixing words and numbers such as we may find in our Results sections. Here, instead of saying that the concentrations for Substance A, B, C, and D were 78, 4.3, 10, and 22 mg/ml, respectively, it is better to rewrite the sentence so that our readers have it perfectly clear what our findings were. In this case, it would look something like this: We found that the concentration of Substance A was 78 mg/ml, for Substance B, 4.3 mg/ml, for Substance C, 10 mg/ml, and for Substance D, 22 mg/ml.

Science is already complex enough, so we should strive to make our writing as clear as possible for the benefit of our audience.

Now, the examples used above are not wrong. The adverb "respectively" means “for each separately and in turn, and in the order mentioned”, and should be used when one has two lists of corresponding items, as explained by Cell Mentor.  It is used incorrectly when there are no corresponding items in the sentence. For example, saying that the flasks were labeled A and B, respectively, is incorrect, because there is nothing that corresponds to A and B. You can find more examples of the correct and incorrect uses of respectively on the website mentioned above, as well as in this tutorial by Springer.

Still, I strongly advise my students to avoid it, because when used incorrectly (and sometimes also when used correctly), it can make our sentences confusing. Science is already complex enough, so we should strive to make our writing as clear as possible for the benefit of our audience.  

Alex Arreola is a Professor at the College of Biological Sciences of the Universidad Autónoma de Nuevo León, in Mexico. She teaches philosophy of science and science communication at the undergraduate and graduate levels, respectively.