Systems and methods are described for attributing online actions to previously delivered electronic advertisements on a plurality of devices using a plurality of device identifier (ID) clusters without use of central IDs. Each device ID cluster is associated with a device, and each device has device characteristics. Each device ID cluster includes one or more device identifiers. Device-related ad impression data and online action data is received. This data includes a device identifier associated with the device. The device identifier is used to identify the device ID cluster associated with the device to which the ad impression was delivered or the online action took place on. Copy devices are selected and paired with respective devices, and the same ad impression data or online action data are assigned to respective copy devices, thereby anonymizing the devices for which the device-related ad impression data or online action data was received.