Q. I am a copyeditor for a tiny scientific journal. I was given the following sentence: It is intriguing to note that BE has 18- to 33-fold the analgesic potency of morphine. I felt that this was incorrect and should have been changed to “18 to 33 times the analgesic potency” or “an 18- to 33-fold greater analgesic potency.” My editor overruled me by telling me that in scientific writing this is acceptable. I believe he is being confused by the fact that dictionaries give times as the definition of -fold (the true meaning of -fold is quite debatable, but that is not my question). I can’t seem to find a good reference for correct usage in this case.
A. Writers and editors in scientific disciplines avoid the use of -fold precisely for this reason: It’s ambiguous. From The CSE Manual: Scientific Style and Format for Authors, Editors, and Publishers, 9th ed. (12.3.3, “-Fold, Factor, and Times”):
Ambiguous:
The increase in the initial volume of 10 mL was 3-fold. (The wording could be interpreted to mean either that the volume increased by 30 mL for a final volume of 40 mL or that the final volume is 30 mL.)
Unambiguous:
The initial volume was 10 mL, and the final volume was 30 mL.
The final volume was 30 mL, 20 mL greater than the initial volume of 10 mL.
The final volume was 3 times the initial volume of 10 mL.
The final volume was 300% of the initial volume of 10 mL.
The final volume represented a 3-fold increase, from 10 to 30 mL.