# Plural or singular use in combination with a list

I quite often see constructions like

The mean value of A, B, and C is 1, 2, and 3, respectively.

I would expect it to be rather

The mean values of A, B, and C are 1, 2, and 3, respectively.

Are both forms acceptable in terms of written language? If so, is one preferable?

Update: From the context I know that both sentences are supposed to mean the following:

The mean value of parameter A is 1, the mean value of parameter B is 2, and the mean value of parameter C is 3.

## 1 Answer

I think `The mean value of A, B, and C` is a single value (not several values like in your first sentence). For example:

The mean value of 1, 3, 5 is 3.

But when you say `The mean values of A, B, and C`, you are talking about the mean value of each element in your sentence separately (the mean value of A, the mean value of B ...)

For example:

``````A = [1, 7], mean value = 4
B = [4, 6], mean value = 5
C = [5, 7], mean value = 6
The mean value for all numbers: 5
``````

The mean values of A, B, and C are 4, 5 and 6, respectively.

and

The mean value of A, B, and C is 5.

• Yes. This is not a question of "which is correct?", but of "what are you trying to say?" If there is one mean value, than you should discuss it in the singular. If there are multiple mean values, presumably one for each of several sets, then it's plural. – Jay Aug 30 '18 at 13:28
• @helen See added information. Both are supposed to mean the same. – Mr. T Aug 30 '18 at 13:40
• @Mr.T OK, what is A? It can be a set of numbers and we are talking about the mean value of these numbers, or imagine several experiments are being done to find the value of A and we decide to consider the mean value of A as the result. – helen Aug 30 '18 at 14:07
• @Mr.T According to your added information, if you want to talk about the mean value of each element, you should use singular. For example: The mean value of parameter A is 1. or The mean value of parameter B is 2. But if you want to talk about multiple mean values, you should use plural. For example: The mean values of parameter A and parameter B are 1 and 2, respectively. – helen Aug 30 '18 at 14:12
• This is exactly my question. The first version, although in common use, is, therefore, simply wrong for the intended meaning? – Mr. T Aug 30 '18 at 14:18