The PUMS are computer-accessible files that contain records for a sample of housing units, with information on the characteristics of the units and the people in them. Within the limits of the sample size and geographic detail, you can use the PUMS to complete several types of tabulations.
The 1970 data collection were prepared by the United States Bureau of the Census. All data released by the U.S. Bureau of the Census are subject to strict confidentiality measures imposed by U.S. legislation (Title 13, U.S. Codes). The census data can be used for statistical purposes only. The PUMS records contain information on the characteristics of housing units and the people in them. The PUMS are extracted from the census data in a manner that avoids disclosure of information that can identify households or individuals. To protect the confidentiality of the respondents, any information that would identify a household or an individual is excluded.
Microdata records identify no geographic area with fewer than 100,000 inhabitants. Microdata samples include only a small fraction of the population, drastically limiting the chance that the record of a given individual is even contained in a PUMS file, much less identifiable.
The datafile is documented in a codebook containing a data dictionary and supporting appendix information.
The 1970 dataset files are hierarchical ASCII 120-character numeric records with no newlines delineating the records. It includes all persons and households within the United States. Geographic identification of the location of the sampled households includes Census regions and divisions (e.g., Standard Metropolitan Areas (SMAs) and State Economic Areas (SEAs)), and each state.
The 1970 Public Use Sample is a representative sample of the records from the 1970 census sample questionnaires. The primary sample size is 1 person in 100, or one sample unit ("unit" refers to a household, vacant unit, or person in group quarters) for every 100 such units in the population. For each household, information is provided about the housing unit itself as well as the characteristics of each person therein.
Each household record is followed by a varying number of person records (one for each member of the household or none if a vacant unit). Each neighborhood characteristic sample is followed by the housing unit records sampled within the neighborhood, which are associated with person records.
There are two types of records stored in the files: Household Records: which contain variables describing the location and composition of the household. Person Records: which contain demographic variables such as nativity, marital status, family membership, and occupation.
Each household record is followed by a varying number of person records (one for each member of the household). Data items in this collection include the individual responses to the basic social, demographic, and economic questions asked of the population in the 1970 Census of Population and Housing.
Information from the census was derived either from questions asked of the entire population or from questions asked of only a sample of the population. Those questions asked about every person and housing unit are called 100-percent or short-form questions. The others are called sample or long-form questions.
Those households receiving the short-form questionnaires were asked only the 100-percent questions, and those receiving the long form were asked both the 100-percent questions and the sample questions. Sampling rates vary depending on geographic location and population size. During the 1970 decennial census, two different long forms were used yielding two different filetypes (the 1 in 1000 5% sample and the 1 in 1000 15% sample, as well as, the 1 in 100 equivalent files.
PUMS data contain a sample of the individual long-form census records showing most population and housing characteristics with identifying information removed.
The coding system varies for each census, so it is important to have access to the codebook for each census in order to assess the meaning of a specific field in a census record and its comparability across censuses. Very little comparability exists between geographic identifiers on each of the previous files, but housing and population characteristics are similar.
The sample questionnaires were edited for completeness and consistency, and substitutions or allocations for any missing data were made. Allocation flags appear at the end of each record to indicate when an item has been allocated. A user wishing to tabulate only actually observed values can eliminate variables with allocated values.
For additional information concerning particular subject matter topics on the files, contact Population Division, (301) 763-7962, or Housing Division, (301) 763-2873, Bureau of the Census, Washington, D.C. 20233.