【正文】 xperiential Experiential word of mouth is the most mon and powerful form, typically accounting for 50 to 80 percent of wordofmouth activity in any given product category. It results from a consumer’s direct experience with a product or service, largely when that experience deviates from what’s expected. Consumers rarely plain about or praise a pany when they receive what they expect.) Complaints when airlines lose luggage are classic example of experiential word of mouth, which adversely affects brand sentiment and, ultimately, equity, reducing both receptiveness to traditional marketing and the effect of positive word of mouth from other sources. Positive word of mouth, on the other hand,can generate a tailwind for a product or service. Consequential Marketing activities also can trigger word of mouth. The most mon is what we call consequential word of mouth, which occurs when consumers directly exposed to traditional marketing campaigns pass on messages about them or brands they publicize. The impact of those messages on consumers is often stronger than the direct effect of advertisements, because marketing campaigns that trigger positive word of mouth have paratively higher campaign reach and influence. Marketers need to consider both the direct and the passon effects of word of mouth when determining the message and media mix that maximizes the return on their investments. Intentional A less mon form of word of mouth is intentional—for example, when marketers use celebrity endorsements to trigger positive buzz for product launches. Few panies invest in generating intentional word of mouth, partly because its effects are difficult to measure and because many marketers are unsure if they can successfully execute intentional word ofmouth campaigns. What marketers need for all three forms of word of mouth is a way to understand and measure its impact and financial ramifications, both good and bad. Wordofmouth equity A starting point has been to count the number of remendations and dissuasions for a given product. There’s an appealing power and simplicity to this approach, but also a challenge: it’s difficult for marketers to account for variability in the power of different kinds of wordofmouth messages. After all, a consumer is significantly more likely to buy a product as a result of a remendation made by a family member than by a stranger. These two kinds of remendations constitute a single message, yet the difference in their impact on the receiver’s behavior is immense. In fact, our research shows that a highimpact remendation—from a trusted friend conveying a relevant message, for example—is up to 50 times more likely to trigger a purchase than is a lowimpact remendation. To assess the impact of these different kinds of remendations, we developed a way to calculate what we call wordofmouth equity. It represents the average sales impact of a brand message multiplied by the number of wordofmouth messages. By looking at the impact—as well as the volume—of these messages, this metric lets a marketer accurately test their effect on sales and market share for brands, individual campaigns, and panies as a whole. That impact—in other words, the ability of any one word ofmouth remendation or dissuasion to change behavior—reflects what is said, who says it, and where it is said. It also varies by product category. What’s said is the primary driver of wordofmouth impact. Across most product categories, we found that the content of a message must address important product or service features if it is to influence consumer decisions. In the mobilephone category, for example, design is more important than battery life. In skin care, packaging and ingredients create more powerful word of mouth than do emotional messages about how a product makes people feel. Marketers tend to build campaigns around emotional positioning, yet we found that consumers actually tend to talk—and generate buzz—about functional messages. The second critical driver is the identity of the person who sends a message: the wordof mouth receiver must trust the sender and believe that he or she really knows the product or service in question. Our research does not identify a homogenous group of consumers who are influential across categories: consumers who know cars might influence car buyers but not consumers shopping for beauty products. About 8 to 10 percent of consumers are what we call influentials, whose mon factor is trust and petence. Influentials typically generate three times more wordofmouth messages than noninfluentials do, and each message has four times more impact on a recipient’s purchasing decision. About 1 percent of these people are digital influentials—most notably, bloggers—with disproportionate power. Finally, the environment where word of mouth circulates is crucial to the power of messages. Typically, messages passed within tight, trusted works have less reach but greater impact than those circulated through dispersed munities—in part, because there’s usually a high correlation between people whose opinions we trust and the members of works we most value. That’s why oldfashioned kitchen table remendations and their online equivalents remain so important. After all, a person with 300 friends on Facebook may happily ignore the advice of 290 of them. It’s the small, closeknit work of trusted friends that has the real influence. Wordofmouth equity empowers panies by allowing them to understand word of mouth’s relative impact on brand and product performance. While marketers have always known that the impact can be significant, they may be surprised to learn just how powerful it really is. When Apple’s iPhone was launched in Germany, for example, its share of wordofmouth volume in the mobilephone category—or how many consumer