I got a question from the Peanut Gallery. Natalia from Houston asks:
“Is there any case where a comma is used before ‘and’?
X, Y, and Z? or
X, Y and Z?”
This particular comma is called the “serial comma.” It is also referred to as the Harvard comma or the Oxford comma. It is the comma that comes immediately before a coordinating conjunction (and, or, nor) that precedes the final item in a list of three or more items in a series.
There are two schools of thought on this particular type of comma:
1) Obviously, the folks at Harvard and Oxford like to include it. It mimics the voice pauses when speaking the sentence. It can also resolve ambiguity.
2) The AP Stylebook advises against it, considering it redundant because the conjunction “and” separates the last two items in the series. Omitting it also takes up less space in a line of text.
I follow the SPE Style Guide, which says to use the serial comma before “and.”
Core Labs measured the porosity, permeability, and water saturation of each core plug.
Tomorrow, we’ll cover some examples of how ambiguity can be caused by both leaving the serial comma in and by taking it out