> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/snomed-international-documents/snomed-ct-glossary/s/statistical-classification.md). # statistical classification ## statistical classification A hierarchical organization of terms or ideas that allows aggregation into categories. #### Notes * A *statistical classification* * Allows categories to be counted and compared, without double counting. * Is a monohierarchical classification, which mean that each node in the hierarchy is included in only one node in the level above. Although this avoids double counting, it means that arbitrary decisions are made when a node is naturally related to more than one parent. #### Example * In a *statistical classification* such as ICD-10, *bacterial pneumonia* is related to *lung disorder* or *infectious disorder* , but not to both.

Figure 1: Hierarchy Illustration - Statistical Monohierarchical Classification

* In contrast, a polyhierarchical classification such as SNOMED CT, enables *bacterial pneumonia* to be a subtype of both *lung disorder* and *infectious disorder*. This enables more inclusive analytics and avoids overlooking conditions that are in a different category from the one being analyzed.

Figure 2: Hierarchy Illustration - Subtype Polyhierarchy

## Provide Feedback --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.snomed.org/snomed-international-documents/snomed-ct-glossary/s/statistical-classification.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.