In a research paper, is it appropriate to use the word like meaning similar or similar to? For example the sentence:

Like in Eq.(2), we will substitute y in Eq.(6) to simplify the equation.

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    As long as you, like, don't just stick the word in, like, anywhere.
    – GEdgar
    Aug 1, 2015 at 19:23
  • I had similar concerns a long time ago, but then I got a Referee report written in broken "Russian English" saying that the article is "well written". The Referee wanted more explanations, so I had to rewrite part of the article, and I of course didn't bother with writing style, as it was going to be judged by someone who can't write decent English him/herself. Aug 1, 2015 at 21:42
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    @CountIblis And luckily everybody else who ever read that article also didn't speak proper English.
    – Voo
    Aug 2, 2015 at 9:29
  • @Voo , that was in Phys. Rev. D. there they have the habit of letting the grammar/spelling etc. be fixed later by the typesetters. They send you back a draft version for your feedback, often they will have made some grammatical changes. With so many non-native English speaking physicists, you cannot expect the Referees to give you the right feedback on your use of the English language. Also, you don't want to hinder the development of language; if some way of expressing things is efficient, it will be used and "legalized", even if it isn't strictly correct. Aug 2, 2015 at 17:33
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    @CountIblis My point is that just because the referee can't write decent English, doesn't mean that later readers of the paper won't judge the paper (and thereby implicitly you) based on the writing - it's nigh impossible to not be influenced by such things even if one tries. So while lazy language might not affect the publication process itself, it certainly isn't without consequences.
    – Voo
    Aug 2, 2015 at 17:50

4 Answers 4


The word "like" is perfectly OK, but your use of it in the example sentence is wrong. It should be "as" [[because the clause "Like in Eq. (2)" modifies the verb phrase "will substitute" and thus functions as an adverb. "Like" produces adjective phrases and would be correct if you were modifying a noun.]] For example, it would be correct to write "This simplification is like the one in Eq. (2)."

EDIT: What I wrote about the example sentences is right, but the reason I gave, now in brackets [[...]] above, is wrong. In particular, a "like" phrase can function as an adverb; "he sings like Caruso" is correct. The difference between "like" and "as" (when they express similarity --- both words have several other meanings) is that "like" is a preposition and "as" is a conjunction. So "like" should form a phrase with a noun, e.g., "like the one in Eq. (2)", and "like Caruso". "As" should be followed by a whole clause, like a sentence, but much of that clause is often omitted. Thus, for example, "As in equation (2), we will substitute ..." is an elliptical form of "As we did in equation (2), we will substitute ...".

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    If you were using "similar" then your example should begin with "Similarly to" (an adverb), whereas the example in my answer would use "similar" (an adjective). Aug 1, 2015 at 18:10
  • What about "Just like in equation 2, we will..."? Aug 2, 2015 at 1:54
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    @Pikamander2 No. "Just as in equation 2, we will ...." Aug 2, 2015 at 2:34

This isn't the world's best sentence, but it's not wrong, and it's not a Valley Girl verbal tic. "Similar to the procedure used to derive Eq. (2), we substitute $y$ in Eq. (6) to simplify the equation yielding ...$

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    There's a very simple way to improve the sentence. Replace "like" with "as".
    – Corvus
    Aug 1, 2015 at 18:13
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    As Andreas noted, the sentence is not in accordance with the usual rules of grammar... Aug 1, 2015 at 18:43
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    @P.Windridge, there are not that many fixed rules of English grammar. His answer could do with a citation, and not one to Strunk and White.
    – Bill Barth
    Aug 1, 2015 at 19:43
  • @BillBarth, I would say there are no fixed rules, and we are free to use whatever constructs we want. In poetry we may want to force a rhythm or in literature evoke a specific sensation. You are free to write "this idea sense no make". I think it has a clear meaning. The "rules of thumb" in Strunk and White etc are a non-exhaustive mixture of authoritarian declarations and common usage. Sure there's no need to stick to them. But they are invented to ease communication. Aug 2, 2015 at 8:42
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    I would say that the sentence is wrong. "Like", used in this way, asserts a similarity between equation 2 and the subject of the sentence, "we", but we are not like equation 2. Rather, we are behaving like we did when dealing with equation 2. Aug 2, 2015 at 12:42

"Like" is OK here, but lose the "in". The preposition meaning "similar to" is just "like", not "like in".


"As in" is equally good.

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    In this case, "as in" is much better. "Like" asserts that the subject of the sentence ("we") resembles equation 2, which is not the intended meaning. (Compare, e.g., "Like all competent mathematicians, we substitute y...") Aug 2, 2015 at 12:40

I think that because "like" is used so often in casual conversation, you know, like when you're talking to a friend and she's like and then I'm like . . . and so on, I try to avoid it in more formal papers. You can often find a substitute, "as," "such as," "as though," and so on.

Of course, there are appropriate uses, especially when "like" is being used as a preposition: Martin was so tired that he looked like a zombie.

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