MicrostockGroup

yeah, all that should be a little more user friendly... but to answer your question.

The boxes on this page, lower down to the right is a RPI poll... which is return per image per month.
Take your earnings for the previous month on a site, then divide by the amount of images you have .. and you get an RPI number

earnings on site / images on site = RPI (monthly)

then, on the other polls... which you will get to here
http://www.microstockgroup.com/index.php?action=pollsvote

it is less scientific.  It is mostly to give a general idea of how a site is doing related to the other sites and how that changes over time.

For a basic guideline however...
Give your best site a 10, and your worst site a 1
Then sprinkle everything in between where you feel it fits.  If your best site is 2x better than every other site, you might want to give your best site a 10 and your #2 site a 5 and so on.

And this is in regards to the previous month...

no prob.  and remember
there are no dumb questions 

Err... I actually didn't know what the right hand column was all about either to be honest.

Now you've explained everything I can see it's quite a useful guide. I'll add my stuff to it.

Well - how well do I pay attention - that's what I did - earnings/images.

When I put in my RPI, the RPIs listed as previously submitted don't match what I typed in for the previous month, are they an average of all previous RPI submitted or what?