Bandwagon effect

The bandwagon effect is the pull of the crowd on what we buy. When many people want something, it becomes more attractive to the rest of us, not because it has changed but because they want it. Sometimes that is sensible, since a popular choice is often a good one. Often it is something else: a wish to belong, to keep up or simply to stop wondering whether we are missing what everyone else has found.

Leibenstein’s definition

The idea of jumping on a bandwagon is an old one in politics, but its place in economics dates from 1950. That year Harvey Leibenstein, an economist then at Princeton, published a paper in the Quarterly Journal of Economics taking up a puzzle raised by Oskar Morgenstern. Textbook demand assumed that each buyer decides alone, so a market’s demand is just the sum of individual choices. But in fashion, Morgenstern had pointed out, people buy because others are buying.

Leibenstein separated three kinds of demand that depend on other people or on price rather than on what a product does. The bandwagon effect, he wrote, is the extent to which demand for a good rises because others are consuming it. It reflects the wish to conform, to be in fashion or to get into “the swim of things.” The snob effect is the reverse, where demand falls as others pile in because buyers want to be exclusive. The Veblen effect is demand that rises because a price is high, the conspicuous consumption the economist Thorstein Veblen had described in 1899.

Leibenstein’s paper was theory, worked out with demand curves. The measurements came later.

What experiments found

In a field experiment published in 2009, the economists Hongbin Cai, Yuyu Chen and Hanming Fang tested what happens when restaurant diners learn what other diners order. Some diners were shown a ranking of the five most popular dishes. Demand for those dishes rose by 13 to 20 percent. Diners shown only the names of some sample dishes, with no information about popularity, did not change their orders in any significant way, so it was the signal of other people’s choices that moved them, not simply seeing the dishes named.

A larger experiment showed how the crowd shapes a whole market. The sociologists Matthew Salganik, Peter Dodds and Duncan Watts built an online music site where 14,341 participants could listen to and download 48 songs by unknown bands. Some participants saw only the names of the bands and songs. Others were split into eight separate “worlds” where they could also see how many times each song had been downloaded by earlier visitors in their world. Seeing the counts made popular songs far more popular and made success less predictable. The best songs rarely did badly and the worst rarely did well, but between those extremes, almost any outcome was possible, depending on which songs got an early lead.

Why we follow

Part of it is information. When you do not know which dish, phone or running shoe is good, other people’s choices are a reasonable clue. Part of it is belonging. Owning what your group owns signals that you are one of them, and lacking it can feel like being left out, which is where the bandwagon meets FOMO. And part of it is that some goods really are better when others have them, such as a messaging app or a game your friends play. The trouble is that these reasons blur together, and a purchase made to belong can feel like one made on the merits.

How the crowd builds a chain

Groups come with kits. Say your running group switches to carbon-plated racing shoes, and your trainers suddenly look like a handicap. You buy a $250 pair. Everyone posts their splits from the same brand of GPS watch, so a $400 watch follows. The group signs up for a spring half marathon, so there is a $120 entry fee and $600 for travel and a hotel. Each step matched what the group was doing, and none of them was a decision to spend $1,370 on a hobby you started for free.

How sellers show you the crowd

• Best-seller and trending labels. They tell you what others are choosing before you have looked at anything else.
• Live counts. “1,200 bought in the past month” or “15 people have this in their cart” turn a product page into a crowd.
• Review volume. A rating with thousands of reviews looks safer than a better rating with a few dozen.
• People you follow. Campaigns built around creators and friends make a product look like the choice of your group.
• Waitlists and launch numbers. A long line is an advertisement in itself.

How to step off the wagon

1. Name the problem first. Write down what you need the item to do. If you cannot, the crowd may be the only reason you want it.
2. Ask who the crowd is. A best-seller among professionals or among people with different needs tells you little about your own case.
3. Borrow before you buy. Try a friend’s gear, rent it or wait a season. Many group trends pass before the gear wears out.
4. Give it time. A waiting period such as the 30-day rule separates what you want from what everyone is buying this month.

Where it meets the Diderot effect

Groups define their own sets of things that go together: the right shoes, watch and jacket for a running club, the right tools for a hobby, the right furniture for a certain kind of home. The bandwagon effect sets that standard from outside, and the Diderot effect then makes every piece you lack look like a gap. Our page on how marketers use the Diderot effect shows how sellers stage those sets, and a whole shopping street can do the same, as our playbook on why every high street looks the same explains. When the crowd is your neighbors rather than a club, the same pull goes by another name: keeping up with the Joneses.