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Just to try to illustrate what this data looks like, this is going to be a slide of one typical time series. What you see is the weekly movement in price for Tropicana 64 oz. This is one individual product that the store sells and this is just one store. The top line is price, and price is denoted on the right axis. As you move along weekly in price there is going to be some notion of what my everyday price is. And then occasionally you will get feature deals; a feature is something in a store advertisement that the store sends out. A deal is an internal sign, like a tag on the shelf, that indicates that this is a good buy. You can see that whenever you've got these feature and deals, the price drops.
Although it's not always the case, you can have unannounced price cuts, but the notion is that I have an everyday price and occasionally I drop my price. The bottom black line is movement; you'll notice that whenever you've got this price decrease, movement jumps up. It's just the fundamental relationship that economists say exists between price and demand. Whenever your price is going up, your demand drops, and whenever price goes down, demand increases. Yes?