1. A computer-implemented method comprising: receiving, by a processor, first unique visit interaction data representing interactions with a first entity by a first visitor and second unique visit interaction data representing interactions with a second entity by a second visitor; receiving, by the processor, third unique visit interaction data representing interactions with a third entity by a third visitor; aggregating, by the processor, the first unique visit interaction data with the second unique visit interaction data to produce first unified visit interaction data; aggregating, by the processor, the first unified visit interaction data with the third unique visit interaction data to produce second unified visit interaction data; computing, by the processor using a first visitor stitching algorithm, a first unified visitor level of certainty that the first visitor and the second visitor are the same visitor; computing, by the processor using a second visitor stitching algorithm, a second unified visitor level of certainty that the first, second and third visitors are the same visitor, the second unified visitor level of certainty being different than the first unified level of certainty; and generating, by the processor, a report using: the first unified visit interaction data and the third unique visit interaction data while a user-specified level of certainty is less than or equal to the first unified visitor level of certainty and greater than the second unified visitor level of certainty; the second unified visit interaction data while the user-specified level of certainty is less than or equal to the second unified visitor level of certainty; and each of the first, second and third unique visit interaction data while the user-specified level of certainty is greater than the first and second unified visitor levels of certainty.