Detecting and Preventing Click Fraud
Click fraud prevention is obviously a concern for advertisers, who can now buy software for detecting possible click fraud. It's also an area of ongoing research for the advertising services themselves, who see widespread click fraud as a threat to their advertising revenues. (In a widely reported story, Google's chief financial officer called click fraud a threat to Google's financial health.)
Although most of the burden for detecting and preventing click fraud falls on the advertisers and the advertising services, web site owners can also take steps such as these to combat click fraud:
- Not encouraging or enticing visitors to click ads. Asking visitors to click ads or otherwise unduly drawing attention to the ads is against the advertising service's terms and conditions.
- Carefully monitoring ad clicks. Pay attention to sudden increases in the number of clicks, especially when the ratio of clicks to page impressions (usually referred to as the clickthrough ratio) also climbs.
- Logging server activity. If possible, keep detailed logs of all the pages requested by browsers. Capture not only the time and IP address of a request but other information such as the referring page and the type of browser, easily obtained from standard HTTP headers included with each request.
- Proactively reporting suspicious activity. If you suspect click fraud, immediately report those suspicions to the advertising service. Provide as much information as possible, including extracts from your server logs if necessary.
- Removing ads from certain pages. Sometimes click fraud occurs on only a few pages of a site, especially with depleting click fraud targeted at certain advertisers. Temporarily or permanently removing ads from those pages can protect you from being a party to that fraud, although it will unfortunately reduce your advertising revenues. If you can figure out which ads are being targeted—this usually requires guesswork on your part—you may also be able to get the advertising service to filter out the ads in question.
Constant and open communication with the advertising service is your biggest defense in the war against click fraud. Ultimately, it's the advertising service that determines whether click fraud has occurred and what the consequences are for the site(s) involved. Google has been known to arbitrarily suspend sites from its advertising program for failing to do anything about click fraud, even if those sites didn't actually instigate the fraud.
The truth is that pay-per-click advertising will always be susceptible to some form of click fraud, no matter how sophisticated click fraud detection becomes. The key for Google and other advertising services to be successful with the pay-per-click model in the long term is to minimize the amount of click fraud that occurs. As a web site owner benefiting from the PPC model, you should do your utmost to help the services avoid click fraud.