SAN FRANCISCO (AP) - John Thys still hasn't figured out how much his company has paid Google Inc. for bogus sales referrals caused by ''click fraud'' - a sham aimed at a perceived weakness in the Internet search leader's lucrative advertising network.

But Thys says he has uncovered enough of it to conclude that Google is trying to shortchange his company and thousands of other advertisers by offering refunds totaling $60 million to settle a lawsuit.

Google's offer works out to a $4.50 refund on every $1,000 spent in its vast advertising network over the past 4 1/4 years.

Click fraud is when merchants are billed for fruitless traffic generated by scam artists and mischief makers who repeatedly click on Web links with no intention of buying anything.