They don't, just as they don't get a sense of the average purchase amount per trip. If above-ground parking lots get 20% more traffic, you can expect roughly 20

They don't, just as they don't get a sense of the average purchase amount per trip. If above-ground parking lots get 20% more traffic, you can expect roughly 20% higher retail sales with some error bars based on the historical correlation. The game here is essentially to get noisy signals about companies earlier than the official ones provided by the company. Take satellite pictures of parking lots, do phone surveys of consumers, count trucks leaving supplier companies, whatever. If it's a good predictor, you know upcoming price moves early, and can likely make significant profits off of it.