Hosesaid: Tom Greysaid: Inflation doesn’t only mean that more gold is in the game. It can also mean more supply of resources than demand. Especially after dxp you should not be surprised that supplies are cheaper.
But we haven’t seen the last of actual gp coming into the game. Just look at Jagex trying to introduce spring cleaner with an alchemy function.
If prices drop, it's known as deflation, therefore with regards to the excess supply of resources you mention, you are in fact referring to an instance of deflation in the resource section of the runescape economy, not inflation.
If everything drops in price you would be right to call it deflation. But if resources cost less, players have more money to spend on rarer items which increase in their value. Hence inflation since the supply of money doesn’t diminish.