The adverb ‘respectively’ is often used incorrectly by non-native English speakers. In this short post, we discuss the correct way to use ‘respectively’, focusing on its use in scientific manuscripts.
‘Respectively’ means ‘separately and in the order already mentioned‘. It is used when describing two or more items that refer back to a previous statement. It should only be used if a sentence would be unclear without it.
‘Respectively’ is typically used to save space.
| Without ‘respectively’ | The value of X was 8.7, the value of Y was 9.8, and the value of Z was 5.6. |
| With ‘respectively’ | The values of X, Y, and Z were 8.7, 9.8, and 5.6, respectively. |
Examples of the incorrect use of ‘respectively’
- Trimethoprim and sulfamethoxazole are selective inhibitors of CYP2C9, respectively.
Reason: This is incorrect because there is only one item, CYP2C9, for two items, trimethoprim and sulfamethoxazole, to correspond to. Removing ‘respectively’ would not change the meaning of this sentence, therefore it should not be included.
- Highly selective ratiometric fluorescent sensing for Hg2+ and Au3+, respectively, in aqueous media.
Reason: This is incorrect because there are two items, Hg2+ and Au3+, for one item, highly selective ratiometric fluorescent sensing, to correspond to. Removing ‘respectively’ would not change the meaning of this sentence, therefore it should not be included.
- Maturation of sympathicoblastoma into ganglioneuroma. A report of two patients with 20- and 46-year survivals, respectively.
Reason: This is incorrect because the two patients have not been differentiated, therefore the 20-year survival and 46-year survival do not correspond to any specific patient.
Punctuation
If at the end of a sentence, a comma is placed before ‘respectively’.
The aperture and beam efficiencies were X and Y, respectively.
If in the middle of a sentence, ‘respectively’ is placed between two commas.
The aperture and beam efficiencies were X and Y, respectively, at a beamwidth of Z.