The fractional variability amplitude (F) test (Edelson et. al., 2002, ApJ, 568, 610 and Vaughan et. al., 2003, MNRAS, 345, 1271) is now implemented as of 3rd April 2012.
and is the number of bins, the net rate for the th data point and is the mean of the net rate (= ) and
The error on F is then given by :