The Yost Index is a measure of socioeconomic status (SES) across geographic areas. The index was developed by Kathleen Yost and coauthors in their 2001 paper titled “Socioeconomic status and breast cancer incidence in California for different race/ethnic groups.” There are seven key inputs to creating the Yost index were calculated at the Census block group level (a geographic area smaller than a census tract).
- Educational level: (1) Average number of school years completed
- Income. (2) Median income and (3) share of households below 200% poverty line.
- Housing. (4) Median housing value and (5) median rent,
- Employment. (6) Unemployment rate among those aged ≥16 who were in the workforce and (7) share of employed individuals in a blue collar (vs. white collar) occupation
Yost uses a principal component analysis to create a weighted linear combination of the 7 variables of interest. Jolliffe and Cadima (2016) have a nice overview of what PCA is and how it can be used as well as its limitations.
Using data from both the U.S. Census and the California Cancer Registry, Yost et al. applied this approach to examine the incidence of breast caner and found that:
SES was positively related to breast cancer incidence, and this effect was stronger for Hispanics and Asian/others than for whites and blacks. Adjusting by SES did not eliminate the differences in breast cancer rates among race/ethnic groups. RR differences between the race/ethnic groups were greatest in the lowest SES category and attenuated with increasing SES.
While the Yost paper is a bit old, the index itself lives on in many oncology-related papers which aim to examine disparities in health outcomes. The site Pumphandle actually has 8 years of Yost Index data publicly available here if you would like to explore how to calculate it in practice.
