[STATISTICS-61] Exponential distribution parameterized by the rate (1 / mean)

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Won't Do
• Affects Version/s: 1.0
• Component/s: distribution
• difficulty-level: Easy
• Assignee: Unassigned
• Reporter: Alex Herbert
• Created: 25/Nov/22 12:06
• Updated: 06/Dec/22 11:30
• Resolved: 30/Nov/22 12:39

Description

The exponential distribution is currently parameterized by the mean. This matches the parameterization used by SciPy and Matlab.

The distribution can also be parameterized by the rate. This is the parameterization used by R and Mathematica.

A distribution for the rate can be created as:

double rate = ...
ExponentialDistribution dist = ExponentialDistribution.of(1 / rate);

The formulas for the two parameterization are simple rearrangements. In certain cases direct use of the rate formula can have a large difference to the mean formula.

Investigate the option to provide a rate parameterization as:

ExponentialDistribution dist = ExponentialDistribution.ofRate(rate);