1. An automated computer-implemented method for defining a custom segment in a set of behavioral data, the method comprising: receiving, at a processing circuit, a set of behavioral data associated with a plurality of user devices, the behavioral data including a behavior metric for each of the user-devices resulting from interactions on each of the user devices with at least one of (i) an application having a unique application identifier and (ii) a distributed content item having a unique content item identifier, the behavior metric identifying a particular device of the plurality of user devices, wherein the behavioral data includes retention data for each of the plurality of user devices, the retention data for each user device comprising: a first behavior metric indicating a time at which the user device first launched an application, the time of first launch occurring within a first time period; and a second behavior metric indicating whether the user device launched the application during one or more time periods subsequent to the first time period; identifying, by the processing circuit, multiple cohort groups, each of the cohort groups including one or more of the user devices, the cohort groups are identified based on the behavior metric for each of the user devices, wherein identifying the multiple cohort groups includes: identifying a plurality of discrete first-launch periods; dividing the plurality of user devices into first-launch groups, wherein each first-launch group is associated with one of the first-launch periods and wherein a user device is assigned to a first-launch group if the time at which the user device first launched the application occurred during the first-launch period associated with the first-launch group; and for each first-launch group: identifying one or more discrete time periods which have elapsed since an end of the first-launch period associated with the first-launch group, and assigning each of the user devices within the first-launch group to one or more cohort groups, wherein each cohort group is associated with one of the discrete time periods and wherein a user device is assigned to a cohort group if the user device launched the application during the discrete time period associated with the cohort group; generating, by the processing circuit, a segmentation interface including a graphical visualization of the multiple cohort groups and causing the segmentation interface to be presented via a user interface device, each of the cohort groups in the segmentation interface is presented as a selectable icon; receiving a user selection of one or more of the cohort groups by receiving a selection of one or more of the selectable icons presented via the segmentation interface; defining, by the processing circuit, a custom segment of the behavioral data in response to the user selection, the custom segment is a subset of the behavioral data and is associated with a subset of the user devices; and storing an indication of the custom segment in a non-volatile data storage device.