Are "compared with" and "compared to" participle phrases?

Question

Is "compared with" in the sentence below a participle phrase?

If so, why shouldn't a comma precede it? If not, what role is it playing?

The number of people who regularly eat fast food was much higher compared with the prior year.

Answer 1

The number of people who regularly eat fast food was much higher compared with the prior year.

The italicized part is most certainly a past-participial clause (or phrase if you prefer).

If it were not, then we'd have to class compared as either an adjective or a preposition. As an adjective it would fail to function predicatively:

*The numbers became compared (with the prior year).

*He made the numbers compared (with the prior year).

And there is simply no reason to class it as a preposition since it does not have different syntactic or semantic properties than the verb compare.

Further, this string fits in other constructions that allow a past participial clause:

The numbers were/got compared with the prior year. [passive]

We had/got/saw the numbers compared with the prior year. [complex catenative]

When compared with the prior year, the number of people who regularly eat fast food was much higher. [complement of when]

There is no need to move it to a different category if its use can be explained by properties common to all past participles of transitive verbs.

As far as the comma goes, that's punctuation and opinions differ, so put a comma there if you like. In any case, it's an adjunct (modifier or supplement) in clause structure - not syntactically licensed by any of the other parts of the sentence, free to move around, not required.

Answer 2

I do note that some answers here favor the participle phrase/clause analysis, others the prepositional phrase analysis.

However, I noticed that "compared with" in the sentence can be substituted with "than" classified as a preposition in modern grammar.

"The number of people who regularly eat fast food was much higher than the prior year."

By that reasoning, I'll go with the prepositional phrase analysis.

Edit: DW256 convinced me in the comment section that "than" and "compared with" don't have any syntactic equivalence.

But what about "unlike"?

It looks like it can have a similar meaning to "compared with" in the sentence, whether you put it in front or when the comparative -"er" is not present: Unlike the prior year, the number of people who regularly eat fast food was high(er). CGEL treats "unlike" as a preposition.

That for me counts in favor of the prepositional phrase analysis.

Answer 3

That depends. Many people would say that it wasn't a phrase because it was missing a complement. Thus, the complete phrase would be "compared with the prior year" (as noted by PaulTanenbaum in a comment).

Whether it's a participle phrase depends on whether you consider "compared" to be a participle. I do, but others might not (as noted by Araucaria in a comment).

It does not need a comma because it is "essential" (in the grammatical sense of that term). The author apparently believes that the sentence would lose some important information without it (and I agree). If that part of the sentence wasn't so important—perhaps that information was already indicated earlier and the writer only wants to remind the audience of it again—then it could be surrounded by paired punctuation. I'd probably use parentheses instead of commas:

The number of people who regularly eat fast food was much higher (compared with the prior year).