Now in its fourth year, the Click Fraud Index monitors and reports on data gathered from the Click Fraud Network, which provides statistically significant industry PPC data collected from online advertising campaigns for both large and small companies across all the leading search engines, according to the company. Key findings from data reported for Q4 2008 include:

• The overall industry average click fraud rate grew to 17.1 percent for Q4 2008. That's up from 16 percent in Q3 2008 and from the 16.6 percent rate reported for Q4 2007.

• The average click fraud rate of PPC advertisements appearing on search engine content networks, including Google AdSense and the Yahoo Publisher Network, was 28.2 percent. That's up from the 27.1 percent rate reported for Q3 2008 and down slightly from the 28.3 percent rate reported for Q4 2007.

• Traffic from botnets was responsible for 31.4 percent of all click fraud traffic in Q4 2008. That's up from the 27.6 percent rate reported for Q3 2008 and the 22 percent rate reported for Q4 2007.

• In Q4 2008, the greatest percentage of click fraud originating from countries outside North America came from Canada (7.4 percent), Germany (3 percent) and China (2.3 percent).

"Based on the data we tracked in Q4 2008, it seems that the online advertising industry is not immune to the growing tide of cybercrime during this recessionary period," said Tom Cuthbert, president of Click Forensics, in a statement. "Both the overall click fraud rate and the rate of click fraud originating from botnets were the highest ever in Q4 2008. In addition, we've started to see old schemes like click farms re-emerge. Advertisers should pay close attention to these types of threats in their online campaigns throughout the year."

The Click Fraud Index publishes data collected from the Click Fraud Network, the industry's independent third-party click fraud detection service dedicated to helping companies more accurately monitor their online advertising campaigns for pay-per-click fraud.

Click fraud data is tracked and published on a quarterly basis for specific search providers, industries and trends. The service is unique in that it monitors online campaigns for click fraud by correlating data collected from search provider campaigns and the advertisers' own Web sites.

Do you have a comment or question about this article or other e-commerce topics in general? Speak out in the SmallBusinessComputing.com E-Commerce Forum. Join the discussion today!