In GWAS studies, 5 x 10^-8 seems the defacto standard for association. A lesser known threshhold is 1 x 10^-5.
This threshhold is often called "suggestive association."
I am writing to ask, where did this figure come from? Were empirical tests or statistical simulations done to select this level?
I can find many papers that USE this level, but far fewer that JUSTIFY it. Any relevant citations would be welcome, and thank you.