I need to use an abbreviation for "standard deviation". I know I can use "SD", but today i was asked to use "Std. Dev." instead.
Std. can be used as abbreviation for standard.
My question is about the second word in the abbreviation. Is it written with an upper-case "D" (Std. Dev.) or a lower- case "d" (Std. dev.)?
Thank you for your help.