Perception.....

[Riv]

If this was true, then why would they make "HQ Discovery Rate" and "Perception" two different stats?

Because it's the same as STR and Attack Power, or INT and AMP. Perception is the base stat (STR or INT) that influence the chance of finding HQ items, and HQ discovery rate is a direct increase of that chance. At least that's the way i see it.