This is enormous overanalysis of an underpowered study design. N=2 to evaluate what you hypothesise to be a small effect is pointless. Did you perform a power analysis before you started?
I don’t know why others are downvoting this. Almost the first thing I did on opening this article was Cmd+F search for “power.” When I hear about a null result for something I care about, whether the study had enough power to detect a positive result if there is one of the first things I want to know; if the answer is no, then there’s little to be gained by reading it.
I don’t like the jump from “N=2” to “underpowered” (I read a good part of a book on single-case study design), but that’s more analysis than I found skimming and searching through TFA.
Power analysis from before the trial here. We halted because sleep deprivation was unsustainable for me, and we then found out Fitbit was dropping on collaborator’s data anyway, so I’m happy we stopped early and can now do another trial.
Thank you for offering a more constructive comment.
We did a power analysis to set the total number of trials (iirc assumed d=0.5, alpha=0.05, 80% power, so ~30 total test weeks and 10 weeks/person). However, the design proved unsustainable for us and the Fitbit dropped one persons data.
Though in some sense it worked out, we can pursue a better trial now.
This is enormous overanalysis of an underpowered study design. N=2 to evaluate what you hypothesise to be a small effect is pointless. Did you perform a power analysis before you started?
I don’t know why others are downvoting this. Almost the first thing I did on opening this article was Cmd+F search for “power.” When I hear about a null result for something I care about, whether the study had enough power to detect a positive result if there is one of the first things I want to know; if the answer is no, then there’s little to be gained by reading it.
I don’t like the jump from “N=2” to “underpowered” (I read a good part of a book on single-case study design), but that’s more analysis than I found skimming and searching through TFA.
Power analysis from before the trial here. We halted because sleep deprivation was unsustainable for me, and we then found out Fitbit was dropping on collaborator’s data anyway, so I’m happy we stopped early and can now do another trial.
Thank you for offering a more constructive comment.
We did a power analysis to set the total number of trials (iirc assumed d=0.5, alpha=0.05, 80% power, so ~30 total test weeks and 10 weeks/person). However, the design proved unsustainable for us and the Fitbit dropped one persons data.
Though in some sense it worked out, we can pursue a better trial now.