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The difference between e.g., i.e., and namely

Filed on: October 21, 2011 | Written by Yateendra Joshi | Add new comment

Latin abbreviations are increasingly rare in today's scientific writing: the Council of Science Editors recommends and others instead of et al. and such abbreviations as op. cit. and loc. cit., commonly used in citing sources, are seldom seen now.

However, the use of e.g. is not all that rare; sometimes, it is used, incorrectly, for i.e., and this blog post shows how the two are different and how they relate to another abbreviation, viz., which simply means namely.

What the three have in common is that all serve to elaborate the word or words that come before; where they differ relates to the nature of that elaboration, that is whether the elaboration consists of examples, rephrasing, or a list, as shown below.

Consider the sentence “A number of weather variables were recorded, e.g. precipitation, temperature, and relative humidity.” The abbreviation e.g. stands for Latin exempli gratia, which means for example. In the previous sentence, the term “variables” is explained by giving examples of some variables that were recorded. Used thus, the abbreviation implies that precipitation, temperature, and relative humidity were not the only variables recorded; perhaps evaporation, the number of sunshine hours, and the intensity of radiation were also recorded.

If the term precipitation needs to be explained, the author can write “Data on precipitation, i.e. rainfall and snowfall, were collected from local weather offices.” The abbreviation i.e. stands for Latin id est, which means in other words and separates two versions which mean the same, the first version being typically more compact.

Lastly, if all members of a group are to be named - an exhaustive list and not merely an illustrative one - namely, or its Latin form viz. is the correct choice. For example, consider the sentence “The present paper evaluates the effect of major weather variables, namely precipitation, temperature, and relative humidity, on crop growth.” Namely makes it clear that the paper is about the evaluation of only three weather variables, and not about any others such as evaporation and the number of sunshine hours. 


["Publish and prosper" is a series of posts about tips for researchers whose first language is not English but who submit papers to journals published in English. The series touches upon not only writing (spelling, grammar, punctuation, usage, and style) but everything else relevant to publishing research papers that journal editors wish their authors knew.]


Grammar and Punctuation

Filed on: October 22, 2007 | Written by | 6 comments

We often are approached with questions related to grammar. One reason for this entire English grammar curiosity lies in the ambiguity that is prevelant in the language. Here are some rather corful ones (especially for people in life/medical science related fields): 

I have observed that some authors insert a comma after e.g. and i.e. and some do not. What is correct?

Some journals use American English, while some use British English. In the American style of writing, a comma is inserted before and after i.e. and e.g. However, in the British style of writing, a comma is inserted before but not after these abbreviations.

In some research papers, I have seen that there is no comma before etc. When is a comma used before etc.?

A comma is used before etc. when it follows more than one listed item, for example, rivers, lakes, streams, etc. (comma used) but rivers etc. (no comma used).

Should a comma be used before "respectively," at the end of a sentence?

The usage of the comma before "respectively" at the end of a sentence is context specific. If the sentence is long and has many parameters, then use the comma for clarity. If not, the comma may be omitted. Thus, although it may appear as inconsistent usage of comma, it is not in fact an inconsistency issue. Furthermore, it is not a BrE/AmE issue.

Here are a few examples. Remember, these are merely guidelines; use your judgment to use this comma.

  • Drug X was administered to the rats and mice on experimental days 4 and 7 respectively.
  • Her first and second sons were named Mark and Anthony respectively.
  • The values of prostaglandin, EP-12, and catechin in the cholesterol-treated and control groups were 12.6, 4.8, and 3.2, respectively.
  • This third release mixes original compositions and classic covers, opening with the heavy salsa of "Llego La Orquestra" before harking back to Manhattan's Palladium Ballroom with "En El Tiempo Del Palladium" and reminding us of the classic sounds of Tipica 73 and Fania with "Se Formo La Rumba" and "Ahora Si," respectively.

Should the definite article "the" be used with taxonomic names of plants?

There do not appear to be stringent rules for inserting the definite article "the" before the taxonomic names of plants. However, the CBE (pg 423) states that for plants, the names at the rank of family and above are plural in form. Considering this, use of the generic "the" with such names appears to be appropriate.

Consider this sentence, "The Liliaceae are very diverse, and they have been separated in to numerous small families." Here, the sentence describes the family "Liliaceae." Therefore, the name of the family is preceded by the definite article "the."

Now, consider this sentence, "The molecular results show that the habit is not a homologous character in Cereeae." Cereeae is a tribe located in the family Cactaceae. Since the rank "tribe" is placed below "family," the name of the tribe is not preceded by the definite article "the."

Furthermore, taxonomic names at the rank of family and above may sometimes be inserted in parentheses. "Comparative anatomy of tribes Cereeae and Browningieae (Cactaceae)." In such constructions, for example, tribe name (family name) or species name (family name), the taxonomic name is not preceded by the definite article "the."

Note: Similar usage appears to be followed with the taxonomic names of animals, i.e., hierarchies at the level of family and above appear to be preceded by the definite article.

Update 1: We have recently released an ebook "10 Punctuation Rules Every Author Should Know" that can be purchased from the website.


[This is part of the "Grammar" series of posts, which covers everything and anything related to English language grammar.]