This is amazing how everybody give unquestionable reasons and come to different conclusions
IMHO RPI shows exactly portfolio strength, not site one, and averaging gives just a temperature near north pole
I see only one more or less reliable metrics: RP_S_I grouped by portfolio size (for mitigation of size/profitability dependency)
In both cases bucketing may be sufficient to give a picture (e.g. <=25, 100, 500, 1500, >5000
E.g. if I send to SuperDuperStock 600 images, get accepted 150, and sold for $60,
my RPSI of $0.1 will go to <=500 bucket
