Methods, systems, and computer programs encoded on a computer storage medium include receiving, from an advertiser, advertisement criteria associated with an advertisement, the advertisement criteria comprising a first set of criteria and a budget and/or a bid, the advertisement criteria to be used in advertisement auctions for which the advertisement is to be considered for display to users performing online actions; determining a number of users for whom the advertisement was a candidate to be shown based on the first set of criteria associated with the advertisement, but to whom the advertisement was not shown based on the budget and/or bid of the advertisement during a particular period of time; and providing, in a report, information relating to the number of users.