1. A method comprising: receiving an advertising opportunity call at a real-time bid exchange server of an advertising campaign management system, wherein the advertising opportunity call is generated in response to a request to access a webpage at a web browser application on a client machine; generating, via the real-time bid exchange server, an advertising opportunity bid request for the advertising opportunity call, the adverting opportunity bid request providing the opportunity to place a bid to transmit an advertisement for presentation at the client machine, appending, via the real-time bid exchange server, an address of the webpage and a user profile associated with the client machine to the advertising opportunity bid request; transmitting, via the real-time bid exchange server, the advertising opportunity bid request to a demand side platform of the advertising campaign management system; transmitting, via a data management platform of the advertising campaign management system, user data and webpage data to the demand side platform; predicting, via a decision engine of the demand side platform, the likelihood of a conversion event for the advertising opportunity for each of a plurality of advertisements being presented with respect to data hierarchies including one or more of the following: a user cluster of a plurality of users that include a user corresponding to the user profile specified in the bid request, a publisher cluster of a plurality of publishers having a same type as a publisher specified by the bid request, and an advertiser cluster of a plurality of advertisements of a campaign or advertiser to which such each advertisement belongs, wherein predicting the likelihood of the conversion event for each advertisement is based on a probabilistic distribution based on historical data of conversion events for a plurality of advertisements that were served for all of the users belonging to the user cluster, all of the publishers belonging to the publisher cluster, and all of the advertisements belonging to the advertiser cluster; for each advertisement of the plurality of advertisements with a predicted likelihood of a conversion event that exceeds a predetermined threshold, transmitting, from the decision engine, an indication of the particular advertisement and an associated bid value amount for such particular advertisement to the real-time bid exchange; collecting one or more indications and associated bid value amounts at the real-time bid exchange and determining a winning indication corresponding to an advertisement with the highest associated bid value amount; transmitting the location of an ad creative file to the web browser, wherein the ad creative file is located on a host server and corresponds to the advertisement corresponding to the winning indication; and retrieving, via the web browser, the ad creative file and rendering the corresponding advertisement on the webpage at the client machine.