Steps to select an epic:
The due date and the version release dates of the selected epic are included by default in the chart.
Additionally the user can define a custom target date.
Time series points are grouped by the selected time unit. Daily and weekly time units are available.
This options defines the number of periods of the given time unit to take into account
to calculate the forecast.
Thus, if the number is 4 and the time unit is weekly then the mean and standard deviation of the velocity will be calculated based on the velocity of the 4 most recent weeks.