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.