06/12/2007 01:06 pm ET Updated May 25, 2011

Why Do Brides Buy and Grooms Rent?

Why do brides spend thousands of dollars on wedding dresses they will never wear again, while grooms, who will have scores of future occasions that call for formal attire, generally rent a cheap tuxedo? It's an interesting question, since the logic of the situation would seem to dictate the opposite pattern. Why don't grooms buy and brides rent?

This question was posed by my former student Jennifer Dulski as the title of the first of her two "economic naturalist" writing assignments for my introductory economics course. The specific assignment is "to use a principle, or principles, discussed in the course to pose and answer an interesting question about some pattern of events or behavior that you personally have observed."

I tell students that their papers cannot be longer than 500 words and that many of the best ones have been substantially shorter. I ask them to imagine themselves talking to a relative who has never taken a course in economics. The best papers are ones that would be clearly intelligible to such a person, and typically these papers do not use any algebra or graphs.

The economic naturalist writing assignment is my attempt to protect my students from the fate experienced by most introductory economics students in American universities. When these students are given tests designed to probe their knowledge of basic economics six months after taking the course, they do not perform significantly better than others who never took an introductory course. In light of the hundreds of millions of dollars that are devoted to these courses each semester, such performance is nothing short of scandalous. What accounts for it?

Part of the answer, I believe, is that most professors try to teach their students far too much. Instead of asking, "How much can my students absorb today?" they are more likely to ask, "How much can I cover?" And when they cover a lot, they feel they've had a good day. The problem is that when we hurl thousands of ideas and concepts at students over the course of a semester, everything tends to go by in a blur. Nothing really sinks in.

A related difficulty is that introductory economics courses are typically awash with equations and graphs. Formal mathematical analysis has facilitated considerable intellectual progress in economics over the last century. But it is not a particularly good vehicle for trying to teach students introductory economics, most of whom become so distracted by the mathematical details that they never really acquire an intuitive grasp of the underlying economic principles. It's a shame, because only a handful of simple principles do most of the heavy lifting in economics.

As a species, we evolved as storytellers. When people wanted to transmit an idea, they didn't express it in the form of an equation or graph. They told a story. Students can absorb ideas in the form of equations and graphs, but in most cases only with considerable effort. In contrast, an idea that is embedded in a story slides into the human brain like a key into a lock.

The economic naturalist writing assignment plays to the brain's strength. In her attempt to explain why brides buy, Jennifer Dulski began by assuming that on big social occasions, it is more important for women to make a fashion statement than it is for men. It's a strong assumption, but also one that most people find plausible. For a rental company to enable a bride to make a fashion statement, it would have to carry an enormous inventory of gowns in each size -- perhaps 100 or more -- lest she show up for her wedding in the same gown an acquaintance had worn just weeks earlier.

Under the circumstances, each gown would be rented only infrequently, perhaps only once every seven years or so, depending on the size of the market. The upshot is that in order to cover its costs, the rental company would have to charge fees in excess of the purchase price of the gown. And since it would be cheaper to buy the gown, no one would rent.

In contrast, a rental company can serve men, who don't seem to mind wearing the same style suit that others wear, with an inventory of only several suits in each size. Each suit can thus be rented multiple times each year, enabling the company to charge a rental fee of only about a quarter of the suit's purchase price. So for someone trying to save a few bucks, renting becomes an attractive option.

My first economic naturalist writing assignment is due at mid-term, and many students find it difficult to pose a question that seems interesting. But the learning curve for the assignment is steep. By the time the second assignment's due date approaches, near terms end, it is common for students to ask whether they can submit multiple questions. "I've got three great questions, and I just can't decide which one to use," is a common refrain during late-semester office hours.

Here's another example: "Why," asked my former student Sam Tingleff, "do many fast-food restaurants promise a free meal if you are not given a receipt at the time of purchase?" Most people who eat at fast food restaurants are not traveling on expense accounts and are thus unlikely to require meal receipts for reimbursement. Why, then, do so many fast food restaurants post these signs?

Mr. Tingleff began by observing that, to deter theft, owners of restaurants and other retail establishments require cashiers to reconcile the total amount of cash collected during their shifts with the total volume of sales rung up at their registers. If the amount of cash falls short, cashiers are typically responsible for making up the difference.

(Drawing by Mick Stevens) from The Economic Naturalist © Robert H. Frank

One way cashiers can circumvent this control is by neglecting to ring up a proportion of their transactions. This tactic works because it is difficult to match specific changes in a restaurant's food inventory with individual transactions at any given cash register. Thus, if a cashier failed to ring up a customer's $20 meal, he or she could pocket the $20 without creating an accounting discrepancy at the end of the day.

Owners could hire supervisors to verify that cashiers ring up every sale. But that would be expensive. Mr. Tingleff argued that by offering a complimentary meal to anyone who fails to receive a receipt, owners provide an economic incentive for customers to monitor cashiers for free.

By semester's end, it is clear that in the process of completing two economic naturalist writing assignments many student's brains have become substantially rewired. Learning a few simple economic principles and having to find ways to apply them to their own experiences and observations transforms them in a way that traditional introductory courses do not. And the transformation appears durable. For example, many former students seek me out when they return to campus for class reunions, eager to recount the many interesting questions they've posed and answered in the years since they graduated. Unlike the trajectory for students who took traditional introductory courses, their knowledge of the subject actually seems to deepen over time rather than decay.

Learning economics is like earning a new language. The only way to make progress is to speak. The best economic naturalist examples have legs. Your first impulse is to share them with friends. In the process of doing so, the ideas they illustrate sink in a little deeper. And unlike the traditional struggle with equations and graphs, it's all without effort.

Robert H. Frank, an economist at the Johnson School of Management at Cornell University and a Distinguished Senior Fellow at Demos, is the co-author (with Philip Cook) of The Winner-Take-All Society. His latest book, The Economic Naturalist, was published last month by Basic Books. Contact: