Study: Facebook marketing can boost sales

As investors question just how much Facebook is worth, a study from Internet research firm comScore suggests that marketing on the world's most populous online social network can help increase sales.

The report released Tuesday found that people who were fans of Starbucks and Target, or friends of those fans, were more likely to buy something than those who were not fans.

People become fans by hitting a "like" button for a brand's Facebook page and receiving updates about that brand mixed in with content shared by their friends.

In the case of Starbucks Corp., those exposed to the company's message on Facebook were 38 percent more likely than the typical Facebook user to make a purchase in the four weeks that followed. Target Corp. saw a 21 percent lift in the same time frame.

The comScore study came a day after the research firm said that the number of unique visitors to Facebook's website is growing at a slower pace. And it's less than a month after Facebook had a disappointing debut as a public company.

The report was partly commissioned by Facebook Inc., a client of comScore's. It was based on a panel of Internet users who agreed to participate in the study -- a condition that can skew results.

Once a brand has acquired a certain number of fans for its Facebook page, its goal should be to reach as many people as possible, have the brand resonate with them and "hopefully influence consumers to purchase or engage with the brand," comScore said.