> I can’t imagine what gave you that idea.
I can't imagine it being that hard to imagine :) considering this is the second paragraph of wikipedia[1]:
Prices will not all increase at the same rates. Attaching a representative value to a set of prices is an instance of the index number problem. The consumer price index is often used for this purpose; the employment cost index is used for wages in the United States. Differential movement between consumer prices and wages constitutes a change in the standard of living.