I have a sentence with a structure similar to this one:

"When advertisers try to influence the beliefs of consumers about the effects of products they face a tradeoff."

I cannot decide whether I should put a comma after 'products' or if I should omit it. My intuition tells me that I perhaps should, but the first part of the sentence is such an important description of 'they' that it seems possible that it should not be separated by a comma.

Any input is much appreciated.

2 Answers 2


My first reading of the sentence grouped the words "products they face" together. By the time that I encountered "a trade off" I realized that I had done that in error. A comma after products would have alerted me (and other readers) that there was a separation between "products" and "they face" and we would have avoided that error.

My practice is to read the sentence out loud. If I pause during a sentence, it is typically to signal that the sentence is shifting from one focus to another. I then think of inserting a comma or other punctuation to make my intent, as the writer, clear.

And if we are being fussy, I would also suggest that the "they" in "they face" is a bit ambiguous. One could argue that the pronoun represents the last explicit noun (that makes sense). The noun "products" does not make sense. The noun "consumers" might make sense but it is a stretch. I am pretty sure that you intended "Advertisers" to be faced with a trade off, but that linkage is muddy.

Restructuring the sentence gives me "Advertisers face a trade off when they try to influence the beliefs of consumers about the effects of products." This sentence is not particularly elegant but it unambiguous.

  • Points well taken! This was for a scientific article, so I opted for your second suggestion. Clarity above elegance. Thank you for your input.
    – chrstnsn
    May 8, 2020 at 12:29
  • As an adverbial clause, this should always use a comma if it precedes the adjacent clause. The essential/nonessential rules for commas that @chrstnsn has attempted to apply are for relative clauses (a.k.a. adjectival clauses) instead - a related but distinct topic. May 11, 2020 at 12:25

Another suggestion to make the sentence less ambiguous would be: When influencing the beliefs of consumers about the effects of products, advertisers face a tradeoff."

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