When using the overview module to learn about your metrics data in Hootsuite Analytics, it automatically analyzes BOTH the time period you select AND the corresponding time period before that. For example, if you select the previous 7 days, Overview will automatically pull data from the previous 14 days. Why would this be a benefit?
to provide an estimate of future trends
to put your analytics results in a more historical perspective
this is not a feature of the overview module
to make it easier to generate ROI reports for key stakeholders
to add fullness to your metrics reports