This question might probably also fit into Academia.SX. I'm writing my first paper in life sciences and I'm very often seeing asterisks as indicators for statistical significance (*).

I'm wondering if there's a convention on which symbol, and how many of them are to be used to indicate what the significance is, e.g. * for p < 0.05 and *** for p < 0.001?

up vote 8 down vote accepted

Following is the convention:

ns      P > 0.05
*       P ≤ 0.05
**      P ≤ 0.01
***     P ≤ 0.001
****    P ≤ 0.0001

This is correct, but please don't fall in the trap of the star system: The Earth Is Round, p < .05 :-)

The convention is...

* yay, I can publish
** yay, I can publish and not get refuted
*** I have no idea what alpha means
**** my power is unfathomable
***** graphing the data and noting r = 0.98 wasn't good enough

Also, see the references in chi's answer.

  • 7
    Because significance testing leads to so many problems let's convert to using skull and crossbones. – Frank Harrell Nov 1 '12 at 13:11

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