There are more marketing channels aimed at consumers than ever. Yet more than three-quarters of consumers surveyed worldwide find that consumer opinions are the most effective form of advertising, according to a Nielsen study.



Nielsen surveyed Internet users in 47 markets in Europe, Asia Pacific, the Americas and the Middle East on their attitudes toward many types of ads, including television, branded Web sites and consumer-generated content.

"The fact that consumers think opinions posted online are as trustworthy as brand Web sites speaks to the power of online reviews and recommendations," said Debra Aho Williamson, senior analyst at eMarketer.

"It also means that marketers need to focus as much attention on what consumers say about their brands online as they do on creating the brand Web sites themselves," Ms. Williamson said. "The easiest thing to do is to make consumer feedback an essential part of every brand Web site."



A similar study conducted by GFK Roper Consulting on the trustworthiness of sources used to make purchases found that consumers rated word of mouth highest.



In the US, more than nine in 10 respondents to a DoubleClick survey said that a friend's recommendation was the most important influence when it came to buying a product or service.



"In all these studies, word of mouth has more of an impact than traditional forms of advertising," Ms. Williamson said. "Having a word-of-mouth marketing strategy is becoming essential for marketers."