Clayton M. Christensen, Scott Cook, and Taddy Hall

With few exceptions, every job people need or want to do has a social, a functional, and an emotional dimension. If marketers understand each of these dimensions, then they can design a product that's precisely targeted to the job. In other words, the job, not the customer, is the fundamental unit of analysis for a marketer who hopes to develop products that customers will buy.

To see why, consider one fast-food restaurant's effort to improve sales of its milk shakes. (In this example, both the company and the product have been disguised.) Its marketers first defined the market segment by product—milk shakes—and then segmented it further by profiling the demographic and personality characteristics of those customers who frequently bought milk shakes. Next, they invited people who fit this profile to evaluate whether making the shakes thicker, more chocolaty, cheaper, or chunkier would satisfy them better. The panelists gave clear feedback, but the consequent improvements to the product had no impact on sales.

A new researcher then spent a long day in a restaurant seeking to understand the jobs that customers were trying to get done when they hired a milk shake. He chronicled when each milk shake was bought, what other products the customers purchased, whether these consumers were alone or with a group, whether they consumed the shake on the premises or drove off with it, and so on. He was surprised to find that 40 percent of all milk shakes were purchased in the early morning. Most often, these early-morning customers were alone; they did not buy anything else; and they consumed their shakes in their cars.

The researcher then returned to interview the morning customers as they left the restaurant, shake in hand, in an effort to understand what caused them to hire a milk shake. Most bought it to do a similar job: They faced a long, boring commute and needed something to make the drive more interesting. They weren't yet hungry but knew that they would be by 10 a.m.; they wanted to consume something now that would stave off hunger until noon. And they faced constraints: They were in a hurry, they were wearing work clothes, and they had (at most) one free hand.

The researcher inquired further: "Tell me about a time when you were in the same situation but you didn't buy a milk shake. What did you buy instead?" Sometimes, he learned, they bought a bagel. But bagels were too dry. Bagels with cream cheese or jam resulted in sticky fingers and gooey steering wheels. Sometimes these commuters bought a banana, but it didn't last long enough to solve the boring-commute problem. Doughnuts didn't carry people past the 10 a.m. hunger attack. The milk shake, it turned out, did the job better than any of these competitors. It took people twenty minutes to suck the viscous milk shake through the thin straw, addressing the boring-commute problem. They could consume it cleanly with one hand. By 10:00, they felt less hungry than when they tried the alternatives. It didn't matter much that it wasn't a healthy food, because becoming healthy wasn't essential to the job they were hiring the milk shake to do.

The job, not the customer, is the fundamental unit of analysis.

The researcher observed that at other times of the day parents often bought milk shakes, in addition to complete meals, for their children. What job were the parents trying to do? They were exhausted from repeatedly having to say "no" to their kids. They hired milk shakes as an innocuous way to placate their children and feel like loving parents. The researcher observed that the milk shakes didn't do this job very well, though. He saw parents waiting impatiently after they had finished their own meals while their children struggled to suck the thick shakes up through the thin straws.

Customers were hiring milk shakes for two very different jobs. But when marketers had originally asked individual customers who hired a milk shake for either or both jobs which of its attributes they should improve—and when these responses were averaged with those of other customers in the targeted demographic segment—it led to a one-size-fits-none product.

Once they understood the jobs the customers were trying to do, however, it became very clear which improvements to the milk shake would get those jobs done even better and which were irrelevant. How could they tackle the boring-commute job? Make the milk shake even thicker, so it would last longer. And swirl in tiny chunks of fruit, adding a dimension of unpredictability and anticipation to the monotonous morning routine. Just as important, the restaurant chain could deliver the product more effectively by moving the dispensing machine in front of the counter and selling customers a prepaid swipe card so they could dash in, "gas up," and go without getting stuck in the drive-through lane. Addressing the midday and evening job to be done would entail a very different product, of course.

By understanding the job and improving the product's social, functional, and emotional dimensions so that it did the job better, the company's milk shakes would gain share against the real competition—not just competing chains' milk shakes but bananas, boredom, and bagels. This would grow the category, which brings us to an important point: Job-defined markets are generally much larger than product category-defined markets. Marketers who are stuck in the mental trap that equates market size with product categories don't understand whom they are competing against from the customer's point of view.

Notice that knowing how to improve the product did not come from understanding the "typical" customer. It came from understanding the job. Need more evidence?

Pierre Omidyar did not design eBay for the "auction psychographic." He founded it to help people sell personal items. Google was designed for the job of finding information, not for a "search demographic." The unit of analysis in the work that led to Procter & Gamble's stunningly successful Swiffer was the job of cleaning floors, not a demographic or psychographic study of people who mop.

Why do so many marketers try to understand the consumer rather than the job? One reason may be purely historical: In some of the markets in which the tools of modern market research were formulated and tested, such as feminine hygiene or baby care, the job was so closely aligned with the customer demographic that if you understood the customer, you would also understand the job. This coincidence is rare, however. All too frequently, marketers' focus on the customer causes them to target phantom needs.