# Classifications and related statistical standards

## What is a classification?

Generally a statistical classification is created to group a set of related categories in a meaningful, systematic and standard format. The statistical classification is usually exhaustive, has mutually exclusive and well-described categories, and has either a hierarchical structure or a flat structure. A statistical classification usually contains codes and descriptors.

## Why have a classification?

Classifications group and organise information meaningfully and systematically, usually in exhaustive and structured sets of categories. Classifications are generally developed to support policy making and because of that, to organise and present statistics. A primary purpose of a statistical classification is to provide a simplification of the real world and to provide a useful framework for collecting and analysing data from both statistical and administrative collections.

## What is a statistical standard?

A statistical standard provides a comprehensive set of guidelines for surveys and administrative sources collecting information on a particular topic. Components of a standard include:

• rationale
• definition
• classification and coding process
• questionnaire module
• output
• related classifications and standards
• glossary and references.

## Why have statistical standards?

The use of statistical standards permits the repeated collection of statistics on a consistent basis. They also enable the integration of data over time and across different data sources, allowing the use of data beyond the immediate purpose for which it was produced. Standards also reduce the resource requirements associated with many aspects of survey development and maintenance.

## What is coding?

Coding is the process by which a description of an item or activity supplied as a survey response is given a matching coded category. The coded categories are defined in standard classifications. Often alternative descriptions can be linked to a single classification category. The full listing of descriptions (known as synonyms) and their associated codes is called a codefile. The codefile is used by a coding tool to enable automated coding using a computer program, or by an operator selecting the best match from a matched display list on a computer. You can download a coding tool here.