The debate about the value of Facebook fans continues to rage on. I hate raging arguments in the absence of solid evidence. So I was delighted to see that analyst Gina Sverdlov of Forrester Research had applied actual statistical modeling to address the question, in a new report called "The Facebook Factor."

Gina's technique is simple to understand. Using a statistical technique called logistical regression, she examined a large number of factors that potentially contribute to whether a consumer will purchase, consider, or recommend a brand. The technique could work for any brand; the report specifically analyzes Best Buy, Walmart, Coca-Cola, and Blackberry.

The results are very suggestive. Here are some facts from the report.

• For all four brands, being a Facebook fan of the brand boosts purchase, consideration, and recommendation. For example, 79% of Best Buy Facebook fans bought there in the last 12 months vs. 41% of non-fans. And 74% of them recommend Best Buy vs. 38% of non-fans.
• Of all the questions we asked (and there were many), being a Facebook fan had more influence over these behaviors than any other factor. Being a Facebook fan of Best Buy increases the odds that a customer will purchase by 5.3 times; the next closest influence factor is having researched consumer electronics, which only increases the odds of purchase by 1.4 times.

The pattern is repeated for every single behavior and every single brand. For example, having a Walmart nearby doubles the odds that you'll consider buying there, but being a Facebook fan of Walmart increases those odds by more than a factor of four.

Does this mean you should pour your budget into building fans for your brand? No! While there is a strong correlation between these positive behaviors for your brand and being a fan, there's no proof that being a fan causes people to buy, consider, or recommend your brand. If you boost your fan base artificially, those fans will be less avid on average.

What this analysis does show is that fandom is worth something. Your Facebook fans are more likely to buy from you, consider you, and of course, recommend you.

This means that cultivating them with content and interaction on your Facebook brand page is well worth it, because this is where your most enthusiastic customers are. You have the opportunity to supercharge them, not just to buy, but to spread your message. For companies that don't provide these fans what they want -- interaction, content, things to share -- this is a wakeup call. And if your brand doesn't have a Facebook page, this report is proof you're stuck in marketing thinking from the previous century. Use this analysis to justify putting your marketing budget and effort into a Facebook page and the staff to keep it lively.