Here's one of the most prolific errors I see when I edit: i.e. vs. e.g.
What's the difference between these two abbreviations and when do you use them?
First, let's define these terms. I won't bother literally translating the full latin words, let's keep things simple. All you need to remember is this:
- "i.e." means "in other words"
- "e.g." means "for example" (thank you Grammar Girl for this great trick)
So when do you use "i.e." and "e.g.?"
Scientists often like to clarify their writing by adding a parenthetical aside in or at the end of a sentence. This is perfectly fine to do, and it's often very helpful (though be careful about over-doing it). Here's an example:
"Carbon nanotubes have many applications in biology (e.g., drug-delivery and near-IR fluorescence imaging)."
Adding "e.g." to the beginning of the parenthetical statement signals to the reader that the following words are an example of what you've just stated in the sentence. So you can read it as:
"Carbon nanotubes have many applications in biology (for example, drug delivery and near-IR fluorescence imaging)."
What if I were to replace "e.g." with "i.e." in that sentence?
"Carbon nanotubes have many applications in biology (i.e., drug-delivery and near-IR fluorescence imaging)."
It would be incorrect, because the statement would be read as:
"Carbon nanotubes have many applications in biology (in other words, drug-delivery and near-IR fluorescence imaging)."
That doesn't sound right, does it? Drug-delivery and fluorescence imaging aren't actually other words for different applications of carbon nanotubes. They're examples.
Why is this important? After all, isn't the meaning clear enough when we use these abbreviations? Does it really matter which one you use?
I'd say yes, because scientists have to be precise, whether in their experiments or their writing. It's important to say exactly and not approximately what you mean.
Also, there are many scientists who have a deep knowledge of grammar and will notice these kinds of mistakes in your manuscripts. You might think these errors are small and insignificant. However, a grammar-minded scientist who is reviewing your work might consider the writing sloppy if they see a large number of these kinds of mistakes and perhaps unfairly also question the precision of your research. Don't give the reviewer any reason to get in a bad mood, especially when it is so easy to learn the difference between "i.e." and "e.g."
So as you write, and you want to use one of these abbreviations, read the sentence aloud and consider whether it makes more sense to say "for example" or "in other words." Then use the appropriate abbreviation.
p.s. A note on punctuation.
You'll notice in those previous examples that I put a comma after the abbreviations.
So it's "(e.g., drug-delivery)," not "(e.g. drug delivery)."
Again, it's a small thing, but precision counts. I could explain to you why you use a comma here (it has to do with restrictive vs. non-restrictive clauses), but don't worry about it.
Just remember that "i.e." and "e.g." are followed immediately by a comma.