What is a Data Dictionary?

A data dictionary helps potential users better understand what a dataset contains by providing data types, names and definitions for the data elements (i.e. columns) within a dataset - it is part of the dataset's metadata.  The open data portal facilitates capturing this information.  Each dataset allows publishers to edit column properties where you can specify the data type, and provide a name and description for each data element.  Information entered is displayed when someone accesses a dataset and views the dataset primer, see image.  The names and descriptions are also included with derived views (i.e. charts, maps, filtered or aggregated data) created using the dataset.

Column descriptions should provide definition of the column, and where necessary, definitions of terms contained within the column - especially when it contains categorical data.  Where a large number of terms are used, you may need to supplement the column description with a glossary.

Guidelines for Good Definitions:

  1. Stated in the singular (e.g., Active Client not Active Clients)
  2. States what the data element or term is, not what it is not.
  3. Uses a descriptive phrase or sentence(s), including essential characteristics.
  4. Avoids the use of abbreviations and acronyms.  Understanding the meaning of an abbreviation or acronyms is usually limited, and can cause misinterpretation or confusion.
  5. Allows only one possible interpretation.
  6. Avoids extraneous qualifying phrases.
  7. For numerical data, includes how it was measured (i.e. method or methods used), if applicable, and provides the units associated with the measure.
  8. States how the data element or terms are used.
Program Area
Open Data, Metadata, Data Dictionary

Printed from the Iowa Department of Management website on March 21, 2018 at 3:54am.