- Description
- Codes
- Comparability
- Universe
- Availability
- Questionnaire Text
- Flags
- Source Variables
- Editing Procedure
Description
HIK is a universal identifier key used to track individuals across historical censuses.
HIKs are the product of a complex linking process developed by the Multigenerational Longitudinal Panel (MLP) project. The MLP project and a description of the linking process are described at the Multigenerational Longitudinal Panel home page.
Individuals can be linked across time spans as long as 80 years. The linking process matches records across 10, 20, and 30 year census pairs, and these links are then chained together into a single HIK. Because the constituent links include non-adjacent censuses, the chain of links within a HIK can skip over ten and twenty years gaps in which we were unable to identify an individual.
We expect to continue improving the linking algorithm in the coming years, applying new data and techniques. If the relationship between any of the person identifiers (HISTIDs) and a HIK change, the old HIK will be permanently discarded and a new HIK will be generated. Old (obsolete) HIKs will be archived and made available for download. The variable VERSIONHIK indicates the revision number of the census data and the MLP linking database; users working with older versions of the data should be mindful that changes to HIKs can occur with the release of revised data. Please refer to the comparability tab for a discussion of the differences between versions of the MLP linking data.
HIK is a 21-character, consistent individual-level identifier. Only persons who can be linked are assigned a HIK; this variable is blank for those who cannot be linked.
Comparability
This variable is comparable across all available datasets.
IPUMS is continually working to improve the MLP linking method, and makes periodic updates to the data incorporating new data sources and techniques. With each version, some HIKs will be added and some may be retired or suppressed. Please refer to VERSIONHIK for the version number of your MLP data. The MLP Version History page has a complete description of each version of the MLP links.
Universe
- All persons linkable to another census year.
Availability
- 2023: --
- 2022: --
- 2021: --
- 2020: --
- 2019: --
- 2018: --
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- 2016: --
- 2015: --
- 2014: --
- 2013: --
- 2012: --
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- 2004: --
- 2003: --
- 2002: --
- 2001: --
- 2000: --
- 1990: --
- 1980: --
- 1970: --
- 1960: --
- 1950: 100%
- 1940: 100%
- 1930: 100%
- 1920: 100%
- 1910: 100%
- 1900: 100%
- 1880: 100%
- 1870: 100%
- 1860: 100%
- 1850: 100%
- 2023: --
- 2022: --
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- 2020: --
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- 2007: --
- 2006: --
- 2005: --
- 2000: --
- 1990: --
- 1980: --
- 1970: --
- 1930: --
- 1920: --
- 1910: --
Flags
This variable has no flags.
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Editing Procedure
There is no editing procedure available for this variable.