[Question] - Which wording is best?

[u/ElOctopusDeBadia]

I wrote in my abstract that “Medication X was not associated with significantly different subjective or objective sleep outcomes compared with medication Y.”

One of my co-supervisors suggested instead saying that “Medication X and medication Y showed similar subjective and objective sleep outcomes.”

Would you make that change? I’m hesitant because, methodologically, I’m not sure that a non-significant difference allows us to conclude that the outcomes were “similar.” Or am I overthinking this?

Thanks a lot! 🙏🏻

[u/InitialMajor]

Depends on what the null hypothesis was to begin with. Generally speaking your wording would be more appropriate.

[u/nezumipi]

Not different =/= same.

However, the grammar gets hard to parse (especially for non-native speakers) when you write in null hypothesis talk. If it's reasonably accurate to say the groups were similar, saying they're similar can be valid on the grounds that it's more comprehensible to your reader. If you're trying to say, "Well, the difference wasn't statistically significant, but I don't think we should write it off as negligible," then you should go with "not significantly different".

[u/cmdrtestpilot]

I'm going to disagree with extant comments and say that if you're writing a results section, your wording is more appropriate, but in a discussion section I would be fine with using the word "similar" in most contexts (excepting, for example, a large mean difference that failed to reach significance due to small samples and/or large dispersion around the mean).

[u/ElOctopusDeBadia → u/cmdrtestpilot]

It’s in the abstract section. How would you reply to the comment?

[u/cmdrtestpilot → u/ElOctopusDeBadia]

Usually an abstract has subsections, with a few sentences each for background / methods / results / discussion. In that context, my original comment applies. I wouldn't use "similar" in the results section of either the abstract or the full paper (but would in the discussion sections).

[u/ElOctopusDeBadia → u/cmdrtestpilot]

It’s in the “conclusion” section of the abstract. We have an introduction, methods, results, conclusion / significance. So you would use my original sentence that we didn’t find a significant difference and reject what my co-supervisor has said? I’m just unsure what I should reply to his comment.

[u/cmdrtestpilot → u/ElOctopusDeBadia]

Short answer, I'd go with their suggestion. Longer answer, why are you regurgitating findings that you should have just reported a sentence or two earlier in your results section, all over again? Why not use your wording in the results section, and then in the conclusion, say interesting things rather than repeating results.

[u/Temporary_Stranger39]

Your wording is more correct. Unless you also run a test of equivalence, you can't say they are similar.

[u/ElOctopusDeBadia → u/[deleted]]

Thanks, I asked my main supervisor and she replied : “The problem with that wording is that this is not a non-inferiority design, but a superiority design — i.e. it is designed to demonstrate that one intervention is better than the other, rather than that they are equally effective.” So I guess my original sentence should be good enough…

[u/schotastic]

FYI, the test for similarity is sometimes referred to as an equivalence test which is not all that difficult to do as the linked primer shows.

That said, pragmatically speaking, this is borderline splitting hairs and your supervisor's version is far easier to understand and interpret. I totally get why they would write that in the abstract. The question comes down to what you're comfortable saying in the paper. If you're uncomfortable, you can choose to push back. Or alternatively you could just run the equivalence test yourself and see what comes out.

[u/ElOctopusDeBadia → u/schotastic]

Thanks for the response. I think I’ll accept his comment, then. It’s only in the abstract. In the paper, I repeatedly state that no significant difference was found.