No abstract

No abstract

No abstract

Yeow et al. found a median one-second difference in time to insertion of a tracheal tube with successful ventilation using a novel cricothroidotomy introducer compared with scalpel cricothroidotomy (85 s vs. 84 s, respectively) [1].However, despite the novel introducer having the greater median, the authors concluded its insertion was faster, with a p value (Wilcoxon's Signed Ranks (WSR) test) of 0.030.In fact, the study was powered to demonstrate whether the insertion times for a pair of techniques differed by more than a threshold value of 45 s, based on a previous study [2]. This calculation is based on the assumption of a normal distribution, but the authors noted that their data were not normally distributed. In addition, their groups were paired rather than randomised, further invalidating the assumptions underlying their power calculation.Re-analysing their data appropriately by comparing a difference between means (assuming these are similar to the medians) of one second would not have yielded a statistically significant result. In effect, the statistical significance reported was disconnected from the authors' original power calculation. Based on their findings, a future study would require 200,992 participants across both groups, to detect a statistically significant one-second difference between means (80% power, a error 0.05).Regarding their use of the WSR test, it is unclear what their null hypothesis was, and, therefore, to what measure the p value related. The only indication from the paper is that the p value appeared to relate to a comparison of the medians, as it is noted immediately following the comparison of medians (IQR [range]).