The Price-Quality Frontier

If you are an economist (which I am), it is natural to draw graphs that tell you useful things about restaurants. The x-axis indicates price (how much the restaurant costs) and the y-axis indicates quality (how much I liked the restaurant). Any restaurant can then be described by a point. This neglects the possibility that I might like a restaurant in some moods or for some purposes but not others, but it simplifies things considerably. Naturally, I prefer restaurants which are high up (good) and far to the left (cheap). Generally, you get what you pay for, so that more expensive places are better; most restaurants fall roughly from lower-left to upper-right. Absent a desire for variety, one would never want to go to a restaurant if there was another which was above it (better) and to the left (cheaper). The price quality frontier is the line drawn to connect all the restaurants which can't be improved upon without spending more. A restaurant is within or inside the price quality frontier if there are restaurants which are both better and cheaper. A restaurant is on the price quality frontier if there are no restaurant which are better without being cheaper. A restaurant extends the price quality frontier if it is on the frontier and the frontier would be lower absent this restaurant.