The Contextual Precision metric is one of several non-deterministic Metric Types Galtea uses to assess how well your RAG pipeline’s retriever prioritizes relevant content. Specifically, it checks whether relevant items in the retrieval_context are ranked higher than irrelevant ones, based on their contribution to answering the user’s query.

High contextual precision means that the retriever is efficiently surfacing the most useful information near the top.

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Evaluation Parameters

To compute the contextual_precision metric, the following are required:

  • input: The user’s query.
  • retrieval_context: The list of retrieved documents or nodes, in ranked order.

This setup allows for a rank-sensitive evaluation of retrieval effectiveness.

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How Is It Calculated?

The score is calculated as follows:

  1. Relevance Annotation: An LLM identifies which items in the retrieval_context are relevant to the input.
  2. Ranking Evaluation: It checks whether relevant items appear near the top of the list.

The metric is computed using a simplified formula:

Contextual Precision=1Number of relevant items∑k=1n(Number of relevant items in top-kk)\text{Contextual Precision} = \frac{1}{\text{Number of relevant items}}\sum_{k=1}^{n}\left( \frac{\text{Number of relevant items in top-k}}{k}\right)

Where k is a configurable cutoff (e.g., top 5 or top 10). This helps gauge whether the most useful content is easily accessible to the generator.

This metric was incorporated to the Galtea platform from the open source library deepeval, for more information you can also visit their documentation.