Findings from a new report from Forrester Research and GSI Commerce are somewhat surprising, in that the study suggests that social media has very little impact on purchasing behavior. The results seem contrary to other reports with headlines such as Social Media Marketing Spend to Hit $3.1 Billion by 2014 and 5 Ways Facebook’s Open Graph Will Impact E-commerce.

I think the study paints a broad stroke, and social media’s impact on eCommerce is vast in some respects and limited in others. Having a Facebook presence simply isn’t enough to impact sales; it’s too often just another channel for one-sided marketing. However, giving loyal customers rewards such as referral credits for sharing your site, or creating social media contests, such as ideeli’s Twitter-based Flash Friday giveaways, seem to have a bigger impact on sales because of the engagement factor, and because a friend who recommends a site or product generally carries more weight than a marketer who’s hocking their wares to the general public.