> ## Documentation Index
> Fetch the complete documentation index at: https://docs.activeviam.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ES (model variation) lookback

<Badge color="gray" size="lg">[es](../tags/es)</Badge>
<Badge color="gray" size="lg">[Lookback](../tags/lookback)</Badge>

<sup>[es](../tags/es)</sup> <sup>[Lookback](../tags/lookback)</sup>

|                 |                                                                                                                                           |
| --------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| **Description** | The measure showing contributors to the ES (Model Variation) avg calculation                                                              |
| **Reference**   | [\[MAR33.5\]](https://www.bis.org/basel_framework/chapter/MAR/33.htm?inforce=20230101\&published=20200327#paragraph_MAR_33_20230101_33_5) |

The measure helps to validate **ES (Model Variation) avg** calculation and inspect actual contributors to spot potential data quality issues, such as spikes or missing values.

The ES (Model Variation) measure is the ratio of the ES (Liquidity Adj.) measures for the reduced and full sets of risk factors (over the current data set). i.e. ES\_\{R,C} / ES\_\{F,C}. As per MAR33.5 (2) (b), this ratio should average over 75% for the last 12 weeks.

Note: the lookback horizon, for instance 60 days, can be changed to a shorter or longer observation window using **CA-Lookback** context value.