A mildly profane tweet I saw recently took people to task for confusing i.e. and e.g. — something I never had to worry about when I worked for daily newspapers. We never let these abbreviations into print. Now, I work for publications that do use i.e. and e.g., and I sometimes run across uses I must puzzle over.
The abbreviation i.e. stands for the Latin id est, meaning “that is,” and it is used before explanatory words. Bryan A. Garner in “Garner’s American Usage” says that you can usually substitute “namely,” a word that is more easily understood. You should follow i.e. with something that makes it clear what you are writing about.
The prosecution introduced its strongest piece of evidence, i.e., the knife found at the scene.
The abbreviation e.g. stands for the Latin exempli gratia, meaning “for example,” and it precedes examples. It could be replaced by the phrase “for example.”
The defense focused on evidence not found at the scene, e.g., the defendant’s fingerprints, bloody footprints leading away from the scene, signs of force entry.
I think I will go out on a limb here and say that if you are writing for most people — not people who are used to reading Latin phrases — you should avoid i.e. and e.g.