What does a heat map show in Cluster Visualization?

A heat map in cluster visualization effectively displays the concentration of relevant documents within specific clusters. By using color gradients, it visually represents areas where there is a high density of pertinent information, helping to identify clusters that contain a significant number of related documents. This concentration aspect allows project managers and data analysts to quickly assess which clusters are the most informative or significant in terms of content relevance.

In this context, the other options address different aspects of data visualization or document analysis. Document structure pertains to the organization or layout of the documents themselves rather than their relevance or concentration in clusters. Cluster distribution focuses on how clusters are spread out or arranged geographically or contextually, which does not specifically indicate the relevance of documents within those clusters. Document age relates to the timeframe or currency of the documents and is not a direct measure of their topical concentration. Each of these perspectives provides useful information but does not encapsulate the primary function of a heat map in demonstrating the density or relevance of documents within clusters.