MarketingExperiments Journal has posted some great research findings online about how a PR campaign they did with Politis Communications was 56.3 percent less expensive than PPC for one site and 21.4 percent less expensive for another site. But that’s not all, the campaigns were also much more effective.

“However, the superior short-term ROI on press releases is just the beginning of the story.

In addition to delivering thousands of new visitors at a very low cost per visit…

PR will result in hundreds or even thousands of new links to your site. PPC will not.
PR will result in follow-up articles and interviews. PPC will not.
PR will result in invitations to speak and write. PPC will not.
PR can build your brand quickly and extensively through exposure on network TV and in national publications. PPC will not.

In short, our tests lead us to believe that PR is extraordinarily under-utilized in the online industry, and that companies should conduct their own tests internally to determine both the short-term and longer-term benefits of PR.”