The price index is a collection of NYMEX or Plains gas prices by production date. These prices can be found online and can give you a better idea of what you should be paid for. You will need the price index set up first before you create a quantity basis accrual definition. The price index is set up by production month. You can set it up with daily price and have it calculate a monthly average, or just update the table once a month to show the new price for that given month. Also see First Purchaser Price Index for more detail.
