I want to say: We focused on X, using Y. Is it correct to put a comma before "using"?

I don't want to write We focused on X and used Y. because I find it ambiguous: it is unclear whether Y was done to achieve X, or Y was done in addition to X.

I don't want to write We focused on X using Y. because it is then unclear whether I used Y myself, or simply that I was interested in "X using Y".

Example: We focused on patient outcome prediction, using dynamic Bayesian networks to model patients' progression throughout their stay in the ICU.

  • We used Y to focus on X? Jan 19, 2015 at 1:07
  • @PeterShor Thanks, sounds like a good alternative, but I don't feel it fits well the sentence I had in mind (which I have now added in the question) :( Jan 19, 2015 at 1:21
  • Since the focus is on "X", I would use a comma after to emphasize it.
    – user3169
    Jan 19, 2015 at 1:52

4 Answers 4


You got it right. The comma is not only allowed—it is effective in adding clarity, as well as accurately indicating a normal spoken pause


Though I can't quote a rule, I would naturally pause after the first phrase (i.e. put in a comma) only if the sentence continued, e.g. "We focused on X, using Y, to do Z." Here are examples of the two, as I would speak:

We focused on cleaning using detergent rather than solvent.

We focused on cleaning, using detergent rather than solvent, to avoid fire hazard.

  • Your second example just propagates a different ambiguity. It might seem contrived, but maybe you cleaned to avoid the fire hazard, and you're just reminding us you happened to use detergent rather than solvent. We can only resolve the ambiguity by using pragmatics/common sense (and by knowing that solvents are a fire risk). In other syntactically identical examples this approach won't always work. Jan 19, 2015 at 2:30

We focused on X, using Y.

We can't omit the comma from the sentence. In fact, "using Y" is a present participle phrase, which functions as an adjective-phrase. In the sentence, this phrase modifies the pronoun "we", which means we used Y to focus on X. In this case, the comma is necessary. If you don'nt put the comma, the participle phrase will modify Y, which means that "we focused on X that used Y. Pls look at the following examples to find out the difference that sentences make with/without a comma:

I saw him walking along the road (the participle phrase modifies "him"

I saw him, walking along the road (the phrase modifies "I")

He loves his glasses, wearing even at night. (the phrase modifies "he".

He loves his glasses wearing even at night (the phrase modifies his glasses, which makes no sense).


The presence of the comma here is a necessity since without it, the sentence would be unclear. It is used here as an identifier of sorts. Your sentence is not only acceptable, it is clear and in its perfect form as well.

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