A method including tracking usage data for users using a first channel and a second channel. The method also can include performing a classification of first users of the users into a first group and second users of the users into a second group. The classification can be based on the usage data. The method additionally can include, for each impression of a content element of content elements being displayed on a website to a user of the users, tracking impression response data including (a) whether the user is grouped into the first group or the second group, and (b) response data including: (i) a first response by the user to the content element in the first channel, and (ii) a second response by the user to the content element in the second channel. The method further can include receiving a request from a first user of the users to display a webpage of the website. The method additionally can include generating the webpage to include a selected content element from among the content elements. The selected content element can be selected based on the classification of the first user and the impression response data for the content elements. Other embodiments of related systems and methods are disclosed.