Abstract: Traffic quality on online properties may be assessed continually, and the traffic quality may be used to determine the price of a click-through for an ad placed on the web property. Advertisers bid on keywords, and the bids are used by an advertising engine to place ads on web pages and other online properties. A benchmark price may be set based on the bids. When a user clicks on (or otherwise activates) an ad, the advertiser pays an amount for the click that is based on the benchmark price and on the traffic quality of the property on which the ad had been placed. Machine learning may be used to create a model that predicts traffic quality based on observable feature of a property, thereby allowing the traffic quality of a property to be assessed in real time rather than historically.