Consultation Services

NIOSH offers consultation for industry and occupation coding to researchers and coders for their specific coding projects. To request help or learn more about NIOCCS, please contact the NIOCCS Support Team in one of three ways:

  1. Submit a question or suggestion using the NIOCCS form
  2. Email us at
  3. Contact one of the following NIOSH staff:
    1. Pam Schumacher, 513-458-7133
    2. John Lu, 513-841-4565
    3. Susan Nowlin, 513-841-4467

Frequently Asked Questions (FAQ) about Industry and Occupation Coding

Many data sets contain narrative text for industry and occupation, including:

  • Vital records systems (death and birth certificates)
  • Cancer registries
  • Worker’s compensation systems
  • Healthcare records
  • Health Surveys

The collection of industry and occupation (I&O) information serves many purposes:

  • To associate specific health outcomes (e.g., a particular cancer or cause of death) with certain industries and/or occupations
  • To identify areas in need of further research
  • To assess socioeconomic status and identify persons who may be at high-risk of disease or injury.

This type of information can be used by public health workers, industrial organizations, employers, healthcare providers and others to provide the best possible hazard abatement and control, and safety and health programs for workers.

Industry Classification

Written responses to the industry questions are coded using the industry classification system developed for Census 2000 and modified in 2002 and again in 2007. This system consists of 269 categories for employed people, including military, classified into 20 sectors. The modified 2007 census industry classification was developed from the 2007 North American Industry Classification System (NAICS) published by the Executive Office of the President, Office of Management and Budget. The NAICS was developed to increase comparability in industry definitions between the United States, Mexico, and Canada. It provides industry classifications that group establishments into industries based on the activities in which they are primarily engaged. The NAICS was created for establishment designations. Because of potential disclosure issues, the census industry classification system, while defined in NAICS terms, cannot reflect the full detail for all categories that the NAICS provides.

Occupation Classification

Occupation data is coded based on the detailed classification systems developed for Census 2000 and modified in 2002. This system consists of 509 specific occupational categories, for employed people, including military, arranged into 23 major occupational groups. This classification was developed based on the Standard Occupational Classification (SOC) Manual: 2000, published by the Executive Office of the President, Office of Management and Budget.


Both the industrial and occupational classification systems for Census 2000 were changed compared to the ones used for the 1990 Census.

Industry: The international policy committee that designed the NAICS set out to create a new classification system rather than simply revise the Standard Industrial Classification (SIC) used prior to 1997. The NAICS expanded the SIC to include industries in Canada and Mexico with those in the United States, and changed the numbering scheme from a 4-digit to a 6-digit system. In spite of these changes, the structure of the 1997 NAICS is not drastically different from the structure of the Standard Industrial Classification for most NAICS sectors. Therefore, crosswalks between the 1990 Census (which was based on the SIC) to the Census 2000 industry classification (which is based on the NAICS) through the two standards is fairly straightforward.

Occupation: The federal interagency SOC Revision Policy Committee (SOCRPC) decided similarly to rearrange the entire structure of the standard occupational classification rather than to start with the old SOC and simply try to make improvements, resulting in major changes. Analysis of occupational data across time will, as a consequence, be much more challenging.

In 2002, all Census codes were modified from 3-digit codes to 4-digit codes.

Page last reviewed: January 13, 2016