# Apostrophe after a surname

There is a lot of statistical criteria/tests (statistics) named after a statistician/mathematician/biologist/economist, etc. But for instance, this and this examples have different spelling...
Do I have to write an apostrophe after a surname in such a situation or not?

• Find what someone else wrote and use that.
– Sam
Commented Oct 20, 2011 at 4:26
• – abc
Commented Oct 20, 2011 at 11:29
• An interesting case. There is a theorem that is often incorrectly written Stoke's Theorem. It should be Stokes' Theorem or Stokes's Theorem, since the man's name was Stokes. Commented Oct 20, 2011 at 14:37
• an example
– abc
Commented Oct 21, 2011 at 2:00

There's an interesting discussion on this topic in Wikipedia talk.

Their conclusion:

I guess we just have to live with the fact that some theorems traditionally have apostrophes (Goedel's incompleteness theorem) and other's don't (Tietze extension theorem); it doesn't make sense to have a general rule of style there.

Go with tradition if you can find it, or with whatever manual of style you follow otherwise.

It depends on how you refer to it, eg. "Fermat's last theorem" but "the Goldbach conjecture"

• The Goldbach conjecture is sometimes written as Goldbach's conjecture, but you'd never say, The Fermat's last theorem. (unless you were trying to distinguishing it from your cousin Fermat's theorem.
– Sam
Commented Oct 20, 2011 at 4:18
• @Sam - yes if you wrote is as Goldbach's conjecture you would add the apostrophe. It was the first one I could think of that was generally "THE ....."
– mgb
Commented Oct 20, 2011 at 4:20
• Doppler effect comes to mind. It would seem strange to say Doppler's effect. Ohm's Law, conversely, would sound funny as The Ohm Law.
– Sam
Commented Oct 20, 2011 at 4:37