The average click fraud rate for pay-per-click (PPC) advertising was 16.3 percent in the first quarter of 2008, down slightly from the 16.6 percent reported in 4Q07.

16.3 percent is, however, up from the 14.8 percent rate reported in Q1 last year, reports the Click Fraud Index, MarketingCharts writes.

Click Forensics issued the data from the Click Fraud Network, comprised of 4,000 online advertisers and agencies that provide PPC data collected from online ad campaigns across leading search engines.

Other findings for 1Q08:

• The average click-fraud rate of PPC advertisements appearing on search engine content networks (such as Google AdSense and the Yahoo Publisher Network, as well as smaller ones), was 27.8 percent. That's down from the 28.3 percent rate reported for 4Q07 and up from the 21.9 percent average click fraud rate reported for 1Q07.

• 1Q08 click-fraud traffic from botnets was 8 percent higher than click-fraud traffic from botnets in 4Q07.
• In 1Q08, the greatest percentage of click fraud originating from countries outside North America came from Monaco (3.1 percent), Ghana (3.1 percent), and New Caledonia (2.4 percent).

"Our 1Q08 data bears out what industry analysts have suspected for several months - Yahoo and Google seem to be finally filtering out more of the click fraud and non-converting traffic they used to let through," said Tom Cuthbert, president of Click Forensics. "Removing some of these higher-profile abusers appears to be having an effect on lowering the click-fraud rates."

"If advertisers, publishers and ad networks continue to take proactive steps to filter out this lower quality traffic, the click fraud rate could trend downward even further, and that's good news for the entire industry."