# Which is the correct form: “Parameter set”, “parameters set”, or “parameters' set”?

I have sets of parameters like `(1, 2, 3, 5)` or `(3.14, 2.73, 1.44, 1.73)`. They are named, but I do not think it makes any difference. Which form is the correct one to call one general case or example of such things?

1. Parameter set.
2. Parameters set.
3. Parameters' set.

I would opt for choice 2. but I am not really sure. That would impose the plural so maybe choice 1 is correct. Choice 3 sounds really off to me in English, but that would be the direct calque from my native language.

The correct form would be parameter set.

Consider the forms in which set can be applied to objects: when you have a set of pencils, the alternative is pencil set, never pencils set. You'd never see 2. used, except in some strange circumstances, e.g. scissors set, where the word used to refer to one object in the set is plural.

3 is incorrect, because the set doesn't belong to the parameters. Parameters' set would, in some cases, be correct, but not here. An example that comes to mind is where you might refer to a few parameters, then identify the set they belong to with e.g. the aforementioned parameters' set.

• So my hunch was good. Thank you +1 and accept for coming up with a valid example for every case. I would imagine 2. would be correct in cases like `((p1 = 1, p2 = 2), (p1 = 0.5, p2 = 3.13) )`, then it would be set of sets of parameters, so maybe one could call it a `parameters set` although I find it quite murky. – luk32 Aug 16 '13 at 18:52
• Also see the Wikipedia article on noun adjuncts for discussion of the underlying rule and its exceptions. – Bradd Szonye Aug 16 '13 at 20:33

(1, 2, 3, 5) is one parameter set. (1, 2, 3, 5) and (3.14, 2.73, 1.44, 1.73) are two parameter sets.

(1, 2, 3, 5) is a set of parameters. (1, 2, 3, 5) and (3.14, 2.73, 1.44, 1.73) are two sets of parameters.

Details:

(1, 2, 3, 5) is one parameter set. Parameter describes what kind of set.

(1, 2, 3, 5) is a set of parameters. Parameters is plural because it refers to what's in the set. If the set contains more than one parameter, the contents of that set are described in plural form.

• To express the answer from @user49891 in another way: In "set of parameters", parameter is a noun and takes the plural form; in "parameter set", parameter is an adjective, and in English adjectives to not take plural forms. – TrevorD Aug 16 '13 at 23:33