Web use can give retailers clues about which customers to charge more.
My first graduate microeconomics class didn’t start with any grand theories or mathematical proofs. It started with a demonstration. The professor marched us down to a computer lab, divided us into groups of six, and had us participate in a simulated market. Amazingly, the price of the virtual commodity we were trading quickly converged to a single value and stayed there. This was a powerful demonstration of the so-called law of one price, the economic principle that markets produce a single price for a given commodity or good.
Many sellers would love to change that law if they could. If merchants could raise prices for customers who were willing to pay more, they could make a lot more profit. Suppose there are two potential customers for my product — one who would buy it for $100 and another who would be willing to pay $150. If I have to charge them both the same price, I’ll charge $100, so that I can sell two units and make $200. The second customer, who would have been willing to pay a higher price, ends up getting a bargain. In economics lingo, that bargain is called a consumer surplus.
But if I could charge each a different price, I’d charge the first customer $100 and the second one $150, for a total of $250. In this case, the second customer wouldn’t get a bargain. That’s called price discrimination.
Merchants already do a fair amount of price discrimination. A car dealer will try to figure out how much you’re willing to pay by talking to you while you take a test drive, and try to persuade you to pay more. Movie theaters offer discounts to seniors and students — people who are likely to have less money — while charging higher prices for working-age adults. The examples are many and ingenious. But there are limits on these shenanigans. When prices are posted publicly, as with a price tag at a store, everyone sees what everyone else is paying. That makes it a lot harder to charge different prices to different customers.
But in the age of the internet, the price-tag system becomes a lot more tenuous. Shopping online, it’s only me and my computer. When I see a posted price, I tend to assume others are seeing the same, but is that really true?
Blogger James Plunkett has a good rundown of recent evidence on this question. Various online retailers are occasionally caught charging different prices to different customers, including Amazon.com Inc., which said it abandoned the practice back in 2000. Researchers found in 2014 that human shoppers got worse bargains on a number of websites, compared to an automated browser that didn’t reveal its identity.