MOUNTAIN VIEW, Calif., March 21 (UPI) -- Google Inc. has expanded a test of a system that lets advertisers pay only when an ad gets results, the U.S. Internet search and online advertising company says.
The "cost per action" system keeps online ads free unless a user purchases a product, subscribes to a newsletter or takes some other action directly related to the ad's purpose, Google says.
Most Google advertisers now pay when a user clicks on their ad, while some are billed based on how many people view the ad.
Many advertisers find cost-per-action appealing because it greatly reduces their risk, since they are not charged for ads that are ineffective, The New York Times reports.
But Web site publishers consider the system risky since it provides no guarantees they will get paid for the space they offer.
Cost-per-action ads have another advantage for advertisers: They virtually eliminate the problem of click fraud, a scam in which people or computers generate clicks on ads for the sole purpose of getting a payment.
The test is currently limited to about 75 advertisers and 75 publishers, Google says.
