Skip to content Skip to navigation

What Is a Data Dictionary?

A Data Dictionary Definition

A Data Dictionary is a collection of names, definitions, and attributes about data elements that are being used or captured in a database, information system, or part of a research project. It describes the meanings and purposes of data elements within the context of a project, and provides guidance on interpretation, accepted meanings and representation. A Data Dictionary also provides metadata about data elements. The metadata included in a Data Dictionary can assist in defining the scope and characteristics of data elements, as well the rules for their usage and application. 

Why Use a Data Dictionary?

Data Dictionaries are useful for a number of reasons. In short, they:

  • Assist in avoiding data inconsistencies across a project
  • Help define conventions that are to be used across a project
  • Provide consistency in the collection and use of data across multiple members of a research team
  • Make data easier to analyze
  • Enforce the use of Data Standards

What Are Data Standards and Why Should I Use Them?

Data Standards are rules that govern the way data are collected, recorded, and represented. Standards provide a commonly understood reference for the interpretation and use of data sets.

By using standards, researchers in the same disciplines will know that the way their data are being collected and described will be the same across different projects. Using Data Standards as part of a well-crafted Data Dictionary can help increase the usability of your research data, and will ensure that data will be recognizable and usable beyond the immediate research team.


Resources and Examples

AHIMA's Health Data Analysis Toolkit

Northwest Environmental Data Network, Best Practices for Data Dictionary Definitions and Usage

USGS: Data Dictionaries and Thesauri