Hall-Tideman Index

Definition

The Hall-Tideman index is a metric useful for the purpose of measuring Concentration Risk diversity or inequality metrics. An alternative name is Rosenbluth Index.

Details

More precisely, if we have n values $E_i$ summing up to a total of

$E_T = \sum^{n}_{i=1} E_{i}$

and each value fraction is defined as

$w_{i} = \frac{E_i}{E_T}$

Then the HTI index is defined as

$HTI = \frac{1}{2 \sum^{n}_{i=1} i w_{i} - 1}$

See Also

• The Gini Index is a related measure

Implementation

Open Source implementations of the HTI index are available in

• the Python library Concentration Library