1. In a reference to the amount of medication provided to an outpatient, I read “three days’ supply for acute or chronic noncancer pain; seven days for cancer pain or palliative care.” Should days be singular in this expression, or plural? I can’t decide whether it applies to three individual days, one at a time, or a single amount dispensed for three days. And in the second phrase, supply is implied after “seven days.” Should days after seven also have an apostrophe?
“Three days’ supply” is equivalent to “a supply for three days,” and the supply essentially “belongs” to the unit of time, not to the segments of time that constitute that unit, so the construction should be in plural-possessive form, as shown. Also, yes, “seven days” is an elided form of “seven days’ supply,” with the repetition of supply implied, but the apostrophe should not also be omitted. However, the elided form “seven days’” is still awkward, and I recommend using the full phrase: “seven days’ supply.” I also advise replacing the semicolon with a comma and or.
2. Are the apostrophes in this sentence correct?: “The US Department of Labor’s Bureau of Labor Statistics’s 2006 Survey of Occupational Injuries and Illnesses revealed that nearly 15 percent of nonfatal occupational injuries and illnesses happened in the retail trade sector.”
Yes, they’re correct, but the use of two consecutive apostrophized proper names followed by the title of a survey is cumbersome. I recommend relaxing the sentence somewhat to “The US Department of Labor’s 2006 Survey of Occupational Injuries and Illnesses, conducted by the department’s Bureau of Labor Statistics, revealed that nearly 15 percent of nonfatal occupational injuries and illnesses happened in the retail trade sector.” There are still two apostrophes, but at a distance from each other, and one of the proper names is also removed from the long train of capitalized words, and the awkward form Statistics’s is avoided.
3. Please settle a disagreement. A friend told me that adding an apostrophe and an s to Joe and Jane in the following sentence is wrong, but I think it’s correct: “Many celebrities, instead of marrying other famous people, choose to settle down with average Joe’s and Jane’s.”
With rare exceptions (such as in the saying “Mind your p’s and q’s”), an apostrophe should not be employed when creating a plural form, and pluralizing a proper noun is not one of those cases. Simply add an s to each name: “Many celebrities, instead of marrying other famous people, choose to settle down with average Joes and Janes.”