By Renae Rodgers
What is an Extract?
IPUMS users will already be familiar with the concept of an extract, but for those who may just be joining us, we’ll do a brief recap. Public Use data files are often large, unwieldy blocks of data, many variables wide and many many records long. Most analyses will only require a small subset of the available variables in any given dataset, but downloading public data from government agencies is an all-or-nothing endeavor. In addition to offering public use data that is harmonized across time and place, IPUMS allows users to choose only their variables of interest for download. These individualized datasets and accompanying metadata are IPUMS extracts.
What is an Extract Definition?
In short, an IPUMS extract definition is all the information needed to create a user’s personalized extract data file and accompanying metadata – everything short of those files themselves.
An IPUMS extract is defined by:
- The name of the IPUMS collection (e.g. “usa”, “cps”)
- A list of sample names or IDs (to be) included in the extract file
- A list of variable names (to be) included in the extract file
- An extract description (e.g. “2022 ACS demographic variables”)
IPUMS users build these extract definitions piece by piece when they create an extract through the IPUMS website, selecting samples, variables, and formats.