Well, the article was hugely uninformative. QPR is a general concept, but if you want to put a formula to it that can be done many, many different ways (depending on what you value). But going to the guy's website provides this insight into what he's doing.
quote:
How is the QPR number determined?
The QPR is determined by taking the average retail price of a wine with a given score and dividing it by the average retail price for all wines with that score. If the average QPR = 100%, then anything below that represents a better value. Anything above, not so good.
So this guy's unique insight into wine buying is that if you have two equally good bottles of wine to choose from and one costs $20 and the other costs $30, then you should buy the $20 dollar bottle. I wonder how long it took him to come up with that formula?

Unfortunately for him, I think the correct answer is that you buy both (although maybe a few more of the $20 bottle), because that $30 bottle doesn't taste exactly like the $20 bottle and there's something unique about it that makes you want to have it. Or maybe there's something in the flavor profile of the $20 bottle that you don't care for so you only get the $30 bottle.
"Drink wine, and you will sleep well. Sleep, and you will not sin. Avoid sin, and you will be saved. Ergo, drink wine and be saved."
-- Medieval German saying