Abstract: Described herein are methods and apparatus for measuring the effect of an online advertisement campaign on online behavior (searches relevant to the campaign and/or click activity on particular sponsored, algorithmic, and/or third-party links) of exposed users who have received a campaign advertisement. Online events of exposed and unexposed users are logged during a pre-campaign period (before any users receive any campaign advertisements) and a campaign period (when exposed users receive a campaign advertisement). A variety of behavior measurements and metrics may be determined using the logged user events. A metric may indicate the difference of an online activity between exposed and unexposed users during the campaign period or between exposed users during the pre-campaign and campaign periods. A metric may indicate the campaign's effect on an online activity by exposed users during the pre-campaign and campaign period in comparison to the online activity by unexposed users during the same periods.