THE POWER OF WORD OF MOUSE people often say that the best form of promotion is by word of mouth. After all, people normally trust a recommendation from someone they know. But in today's digital world, consumers don't just talk to friends and family members. By posting their opinions online, they can reach thousands of other consumers. What's more, this is a very good way of persuading people to buy things. A recent survey by the Nielsen Company revealed that 70 per cent of consumers trust opinions they find online, which is much higher than the figures for other advertising media, like TV and only slightly lower than opinions of friends. The bad news for companies is that negative opinions can go online as well as good ones. When Adam Brimo, an Australian engineering graduate, was dissatisfied with his mobile phone provider, he decided to set up a website to talk about his experiences. It quickly filled up with posts from other dissatisfied customers. In the end, the company invited him to meet their chief executive, who then gave a public apology. When Dave Carroll, a US musician, took a flight with United Airlines, his guitar was broken during the trip. The airline company refused to pay for the damage, so he wrote three songs about it and uploaded them on You Tube. This was a public relations disaster for the airline, and possibly the reason why their share price dropped by 10 per cent that week. Paul Patterson, a professor of marketing, agrees that companies now have less control over how the public view them but points out that the way to deal with dissatisfied customers is the same as always. Companies just need to react faster in case a customer decides to contact other customers online. Some analysts worry that a company's image could be damaged by a small number of dissatisfied customers. But Hugh Bainbridge from the Australian School of Business says consumers do not believe everything they see online, and that brands are only damaged when a large number of customers are clearly unhappy. Instead of seeing it as a threat, companies should treat this new medium as a useful source of customers' opinions. Perhaps the biggest success story comes from Coca-Cola. In 2008, Dusty Sorg couldn't find a Coke fan page he could join on Facebook, so he downloaded a picture of a Coke can and created his own. Unexpectedly, it was a big hit with other fans. When Coca-Cola found out about it, they didn't try to get control over the page. Instead, they flew Dusty to Atlanta to meet their management team and told him to carry on the good work, with help from a few senior executives from the company. The result was a Facebook page run by a passionate fan and a good PR story for Coca-Cola. That really is a smart use of 'word of mouse’.