A system compares website visitation data sets in response to receiving user input. The system includes a client for processing the input to define one or more data sets as a query to a network, which returns the requested data. The system calculates, for at least one website visitation metric, a difference between values of the website visitation metric for the data sets, and displays one or more reports. In addition, reports can be further adjusted per additional data input. The results enable users to analyze the effects of combinations of factors.