eBay's consumer loyalty, measured by whether they would recommend the brand to a friend, has been slowly eroding through all of 2009, according to YouGov's BrandIndex, a daily consumer-perception research service of brands.

YouGov is a professional research and consulting organization and in 2007, acquired Polimetrix, a venture-funded, non-partisan online polling firm founded by Stanford University Professor Douglas Rivers.

According to YouGov, eBay has seen its BrandIndex "Recommendation" score for adults 18+ drop from 40.9 on January 1st to 36.5 as of October 23rd. A score can range from 100 to -100 and is compiled by subtracting negative feedback from positive. A zero score means equal positive and negative feedback. For the Recommend score, BrandIndex asks respondents: "Would you recommend the brand to a friend?"

YouGov's BrandIndex interviews 5,000 people each weekday from a representative US population sample, more than 1.2 million interviews per year. Respondents are drawn from an online panel of more than 1.5MM individuals. Margin of error is +/- 2%.