To Determine daily average prices, KAYAK usually takes all rates for on a daily basis in advance of departure throughout the last 12 months for flights from London Heathrow Airport to Austin, removes the highest 0.1% to account for outliers, after which takes the normal of many of the values https://www.diigo.com/item/note/aa9i2/dq0n?k=045921ba2939f0bff492c6be7cf9ed7c