Compute the level of variability for a certain period of time.
The level of variability is quantified by
mr, as defined in Prahl (1999).
For constant rate events, it follows a standard normal distribution, i.e. it can be used directly as the significance of variability.
For example usage, see Variability test.
- time_delta : array-like
Time differences between consecutive events
- mr : float
Level of variability
 Prahl (1999), “A fast unbinned test on event clustering in Poisson processes”, Link