Active User calculations
Ref: For the date range January 1 to January 30
The definition as by Google Analytics is
1-Day Active Users: the number of unique users who initiated sessions on your site or app on January 30 (the last day of your date range).
What I understand is it counts the number of unique users for the last day (January 30) of the date range and hence it should be absolute. i.e. it should not change wrt to 1 jan , 2 jan etc..
The line chart shows the plots for 1 jan, 2 Jan etc... till Jan 30. Pls explain the X axis in the chart.