Plural or singular verb for collective term

Question

Should the verb, in the following sentence, be singular or plural?

A series of samples was produced.

In a related question I found a reference. However the text in that reference seems to contradict itself.

Nouns that are “collective” take a singular verb when the group as a whole is meant.

Commonly used collective nouns include “number,” “majority,” “series,” and “variety.”

Note that when collective nouns refer to a singular group as a whole they are often preceded by the word “a”;

Based on these rules, I would expect that, since I am using an indefinite article a series, the singular form of the verb is to be used. However the reference uses plural in an example

A series of western blots were performed to assay protein expression.

Answer 1

Apparently, there are two ways we could go about/around this issue.

1. As Quantified Collective - treating the collective as the quantifiable:

   A {number of people} was offended by my opinion.
   A {lot of houses} was burned down.
   A {truckload of potatoes} was delivered.
   Three {truckloads of potatoes} were delivered.

2. As Quantifying adjective - treating the collective as adjective to quantity the noun:

   {A number of} people were offended by my opinion.
   {A lot of} houses were burned down.
   Not {a few} toes were curmudgeoned by my usage of the word curmudgeon.
   {Few} toes were curmudgeoned by my usage of the word curmudgeon.

The following makes the issue obvious:

"Lot" being used as quantified collective:

A lot of class-A shares was assigned to me to manage.
One lot of class-A shares was assigned to me to manage.
Three lots of class-B shares were assigned to me.

"Lot" being used as quantifying adjective:

{A lot of} shareholders were hurt by Madoff.
{Many} shareholders were hurt by Madoff.
{Twenty} shareholders were hurt by Madoff.

The context should spontaneously indicate collective or adjective usage.

A {box of CPUs} with lot-id 123A456 was registered at outgoing inspection gate.
{A box of} tomatoes were stolen from the warehouse.

"Few" is more likely used as quantifying adjective than as quantified collective, because you would never say,

Three few people were arrested.

(In fact, is "few" even a collective descriptor?)

Answer 2

The noun series can be used in both the singular and the plural; it is invariant.

• One series is all you get.
• Several series are needed to get a real picture.

Since you are using a series, singular concordance is demanded.

Your example of “a series of several things were” looks like an error to me, as the plural of the blots has contaminated the verb, and the writer forgot what the actual subject was.

I am unaware of a series of ever being used as an adjectival premodifer, which would be the only possible excuse for a plural verb here.