I think this is just a very clever form of price discrimination. In my experience, there are two disjoint groups of McDonald's patrons, those who order off the

I think this is just a very clever form of price discrimination. In my experience, there are two disjoint groups of McDonald's patrons, those who order off the combo menu and those who order off the dollar menu. The combo menu doesn't have a 20 piece option and the dollar menu doesn't have a 10 piece option. I think this plays into why they are also visually at opposite ends of the display. The people who are looking at the combo menu are far less price conscious to begin with, and an order of 20 nuggets is going to seem overkill of you are working under the assumption that your meal is going to include a drink and a large portion of fries. However, if you are the kind that mentally debates whether you should shell out the extra dollar for a drink, you might be more than willing to forego the fries for an extra portion of protein. I've found similar tricks are used in vending machines, particularly with the different varieties of crackers. Inevitably, there will be one set near the top of the machine with other expensive items and priced according. However, there is also a half row of ever so slightly different ones further down priced at 2/3 the price. It's all just a matter of satisfying the demand that exists at lower price levels without having to lower the price for everyone. Setting prices using price elasticity assumes you can only offer a single price to all parties. However, cost-conscious shoppers are already going to spend more mental cycles looking for a good deal. By making the more desirable pricing just a little hard to find, you can give them a better deal without butchering your overall profit margin.