Intended for healthcare professionals

Rapid response to:

Endgames Statistical Question

Understanding P values

BMJ 2014; 349 doi: https://doi.org/10.1136/bmj.g4550 (Published 11 July 2014) Cite this as: BMJ 2014;349:g4550

Rapid Response:

Why give value to P value when it is more than critical level of significance?

In the example given in the endgame the P value is 0.449 which is more than critical level of significance (0.05) and hence it is concluded that the difference was statistically not significant hence null hypothesis is not rejected. Another statement that Dr. Sedgewick has made is that the p-value does not tell about the direction and size of the difference. Here I am bit skeptical. Since P value has some value viz., 0.449 then there should be some interpretation such as, some other sample has p value above .449, say P=0.8, then we may infer that difference is less remarkable than the sample with P=0.449. If this is not the case, then why give value of P, why not just say it is >0.05 and hence insignificant.

Competing interests: No competing interests

27 February 2016
Neeru Gupta
Scientist F
Jugal Kishore.
Indian Council of Medical Research
Ansari Nagar, New Delhi-110029