From MarketingExperiments.com:

PR Campaign Delivers Greater Return on Investment Than Pay-Per-Click Advertising, MEC Labs finds

Atlantic Beach, FL (PRWEB) September 28, 2005 -- A new research brief released today by MarketingExperiments.com (MEC) announced that public relations campaigns can cost less and deliver better returns on investment (ROI) than pay-per-click (PPC) advertising campaigns.

The research brief is currently available for free in the Marketing Experiments Journal (http://www.marketingexperiments.com/pr.asp)...

Over a six-month period of time, MEC tested nine news releases covering various topics that were sent out over professional and free newswire services. MEC tracked the direct incoming traffic and backlinks on its site as well as the interview opportunities that resulted from each press release. It also compared the average cost per visit associated with each news release versus both the cost per visit associated with its average optimized PPC campaign and the cost per click for relevant targeted keywords in Google.

Results showed that the cost per click of the public relations efforts was less than the cost to drive traffic to the site through purchasing keywords in a PPC campaign. They also demonstrated that the news releases created significant spikes in site traffic and helped to create a five-fold increase in the number of incoming links to MEC's site...

While most of my clients use paid news release distribution services such as Business Wire or PR Newswire, I would add that, for a low-cost campaign to drive traffic, free news release services such as PR Leap and PRZOOM can be very effective.