The 1959 and 1970 published Soviet censuses list several hundred categories of occupations. Yet far more types of employment exist than are indicated by this number of categories. The Dictionary of Occupational Titles published by the U.S. Department of Labor, for example, is composed of approximately 20,000 jobs. The sparsity of categories in any census is a product of the lengthy process in which (1) specific questions regarding employment are designed; (2) respondents interpret the questions and either answer or fail to answer them; (3) answers are coded into specific occupational categories; and (4) these categories are selected and sometimes grouped together for the purpose of the actual census publications. The selection and grouping of categories are of primary concern since here, as at earlier stages, the potential exists for deliberate or inadvertent distortions and for the compromise of the detail and precision of the census.