Updated: May 22, 2020
Statistics can be a scary subject for students and researchers alike. Aside from getting their stats correct, many people ask editors how they should write their statistical parameters in their papers - none more so than p values.
Is it p, P, p, or P?
The simplest answer is that they are all acceptable, just be consistent with your usage. Note that certain writing styles may require a specific way of representing p values (e.g., APA style wants a lower case, italic 'p').
Leading zero or not?
Often you will see p values represented as p < 0.05 or p < .05. The question often arises as to whether you need to have the leading '0' or not. Again, for the most part, it comes down to being consistent. Some writing styles do specify what they prefer (e.g. APA style indicates that you should not have a leading zero...they use the lack of a zero as a visual indicator that the value can never exceed 1) but outside of that, consistency is king.
Is it p-vlaue or p value?
Most often you will see the hyphen omitted from 'p value'. However, it is not technically incorrect to have the hyphen in place.
Is there a space around the mathematical symbol?
Yes, there should always be a space between 'p' and the mathematical symbol being used, as well as the symbol and the number for the p value (e.g., p < 0.05 NOT p<0.05).
You can also follow us on Twitter for helpful writing tips and the occasional discount! @ExcisionEditing