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

# Covariance and Aggregation Bias

> Learn why Provalytics treats aggregation bias and covariance control as core modeling problems, not afterthoughts.

## Overview

Aggregation bias happens when distinct media behaviors are forced into broad groupings and treated as if they behave the same way.

That can flatten real differences in:

* efficiency
* carryover
* saturation
* incremental contribution

## Why this matters

Modern media systems are full of synchronized launches, overlapping audiences, shared creative, and coordinated channel activity.

If the model ignores covariance and over-aggregates everything, meaningful signal disappears.

## How Provalytics responds

The framework uses covariance-aware estimation, hierarchical regularization, and adaptive structuring to preserve signal integrity while still controlling instability.