Data and Methodology

This issue brief draws from data from the U.S. Census Bureau’s Public Use Microdata Series (PUMS) files for the years 2019 and 2021. These data are frequently used by researchers and policy analysts to derive detailed estimates of population characteristics which are not directly produced as part of the Census Bureau’s American Community Survey (ACS). In contrast to the decennial census which is focused on a 100 percent count of the population, ACS and PUMS data are derived from an ongoing sample of the population, with an emphasis on estimating the characteristics of the population.

These sample-based estimates provide useful information, and in the case of PUMS data can be split by characteristics to produce very detailed estimates of population characteristics. However, these data contain a tradeoff - as samples become more specific to subgroups or locations, the uncertainty about the relationship between the population estimate and the true value for the population also grows. We focus on estimates of the characteristics of the population and omit margins of error from our reporting, however, margins of error have been examined to ensure appropriate interpretation of our analysis.

We use the same approach used in Arts Impact Initiative Issue Brief: The Artist Labor Force: A Statistical Look at Illinois in the Context of the U.S. for identifying the artist labor force. We rely upon 2018 Standard Occupation Codes designated by the National Endowment for the Arts for the study of artists’ employment (see the Technical Appendix for more information).

All wage and income statistics reported in this issue brief are inflation adjusted to 2021 dollars using the CPI-U-RS adjustment factor , so that statistics between 2019 and 2021 can be directly compared to each other.

For the purposes of this analysis, we divide Illinois into eight subregions (Figure 2). These subregions are defined in part by the nature of Public Use Microdata Areas (PUMAs) which are a specialized administrative geography produced by the U.S. Census Bureau that contain approximately 100,000 residents each. Because the American Community Survey relies upon a sample of the population, PUMAs ensure that a sufficient number of surveys are present to produce estimates of the characteristics of the population within that area. We aggregate PUMAs into Illinois subregions and use these subregions to describe the varying characteristics of artists and creative workers and their housing.