Navigating the Landscape of Higher Education: An Interactive Map of Market Concentration in the United States

The United States boasts a vast and complex higher education system, a tapestry woven from countless institutions serving diverse student populations. Understanding the accessibility and competitive dynamics within this system is crucial for students, policymakers, and educators alike. To shed light on these intricate relationships, a novel tool has emerged: the School Concentration Index (SCI). This innovative metric, visualized through an interactive map, offers a granular view of higher education market concentration across the nation. By analyzing driving distances and school enrollment data, the SCI provides a unique lens through which to examine the availability and competitive intensity of higher education opportunities at a local level.

Unpacking the School Concentration Index (SCI)

At its core, the SCI is designed to quantify the degree of market concentration within higher education. Drawing inspiration from indices used by the Department of Justice (DOJ) and the Federal Trade Commission (FTC) to assess market power in various industries, the SCI adapts these principles to the unique context of educational institutions. The index ranges from 0, signifying perfect competition where numerous schools offer comparable enrollment opportunities, to 10,000, representing a complete monopoly where a single institution accounts for all enrollment within a given area.

The SCI is calculated for each zip code tabulation area (ZCTA), which are geographical regions approximating familiar USPS ZIP code service areas. For ease of reading, these are referred to as "zips" throughout this analysis. The calculation of the SCI is rooted in the Herfindahl-Hirschman Index (HHI) model. While the HHI traditionally calculates market share for companies, the SCI calculates the enrollment share for a particular school within a specific ZCTA. The number of schools considered for each ZCTA is determined by the driving distance to those institutions. Users can select different map views, which adjust the driving distance parameters to 30, 45, or 60 minutes, thus influencing the number of schools and total enrollment factored into the SCI for each ZCTA.

The visual representation of the SCI on the interactive map employs a color spectrum to denote market concentration. Green indicates perfect competition, gradually transitioning through yellow, orange, and red hues as market concentration increases. Dark red signifies a highly concentrated market. Notably, zips rendered in maroon on the map denote an "education desert"-an area with no higher education institutions within the defined driving distance. This map represents the first in a series of publications that aim to explore market power within the US higher education system and its potential ramifications on issues such as cost, access, student indebtedness, and future earning potential. The academic year under examination for this data is 2016-2017.

Defining the Variables: A Deeper Dive into the Data

To fully comprehend the insights provided by the SCI map, it is essential to understand the underlying data variables and their definitions. These variables, meticulously compiled and analyzed, form the bedrock of the School Concentration Index and its accompanying visualizations.

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School Concentration Index (SCI)

As previously detailed, the SCI quantifies local market concentration in higher education. It is calculated based on the enrollment share of schools within a defined driving distance of a ZCTA. The range of 0 to 10,000 reflects the spectrum from perfect competition to a complete monopoly. Each ZCTA possesses a unique SCI, determined by the number of schools accessible within 30, 45, or 60 minutes of driving time from at least a portion of that ZCTA.

Number of Schools

This variable represents the total count of higher education institutions considered within the selected driving distance (30, 45, or 60 minutes) from any part of a given ZCTA. This metric provides a direct measure of the sheer number of educational options available to residents within a specific geographic radius.

Enrollment

The enrollment figure for each ZCTA is the aggregated sum of the total student enrollment for all institutions that fall within the defined driving distance. This data is sourced from the IPEDS 12-Month Enrollment Table and is presented as a whole number. It offers insight into the overall student population served by the accessible educational institutions.

25 Mile Zone Population Estimate

Recognizing that population estimates for individual ZCTAs might not always be readily available or directly comparable with the zone-based SCI, this variable provides a broader demographic context. It represents the summation of population estimates for all ZCTAs situated within a 25-mile radius of the selected ZCTA. This "zone-type scale" complements the SCI by offering a sense of the potential student pool within a larger surrounding area. Each $\text{pop}_n$ within this estimate refers to the 5-year population estimate for a specific ZCTA.

Institution Name

The names of the educational institutions included in the analysis are directly sourced from the IPEDS Institutional Characteristics table. This ensures a standardized and comprehensive list of all relevant higher education providers.

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Level of Institution

This variable categorizes the type of degrees or programs offered by an institution. Sourced from the IPEDS Institutional Characteristics table, it allows for differentiation between institutions offering associate's degrees, bachelor's degrees, master's degrees, and so forth. This is crucial for understanding the breadth of educational offerings available.

Control of Institution

The "control" of an institution refers to its governance structure - whether it is public, private not-for-profit, or private for-profit. This information, also obtained from the IPEDS Institutional Characteristics table, is vital for understanding the operational and financial models of the institutions and their implications for students.

Private Not-for-Profit Institution

This specific category within the "Control of Institution" variable defines a private institution where the controlling individual(s) or agency does not receive compensation beyond standard wages, rent, or other operational expenses incurred for assuming risk. This distinction is important for understanding the mission and financial incentives of these organizations.

Population Estimate

This variable provides the estimated total population for a given ZCTA. The data is derived from the American Community Survey's 5-year estimates. It's important to note that these estimates are based on a sample and are therefore subject to sampling variability. For US Territories beyond Puerto Rico, population estimates prior to 2010 were only available at the state level through the Census Bureau's 2010 Census Data.

Median Income Estimate

The Median Income Estimate reflects the median household income within the past 12 months, adjusted for 2016 inflation. This data is sourced from the American Community Survey's 5-year estimates (2012-2016). A lack of a listed median income for a ZCTA indicates insufficient sample observations to compute a reliable estimate. This variable offers insights into the socioeconomic context of different ZCTAs, which can influence educational access and choices.

Data Exclusions and Methodological Considerations

To ensure the integrity and focus of the SCI analysis, certain types of institutions and data were intentionally excluded. These exclusions were made to concentrate the analysis on institutions directly relevant to the typical undergraduate and graduate student experience, excluding highly specialized or administrative entities.

Specifically, the following were excluded:

Institutions offering exclusively advanced degrees: This focuses the analysis on institutions primarily serving undergraduate and early graduate populations, avoiding a disproportionate weighting of highly specialized doctoral or professional programs.
Institutions offering exclusively distance learning degrees: The SCI is primarily concerned with the geographical accessibility of physical campuses and the local market dynamics they create. Institutions operating solely online do not fit this framework.
Schools where the level and control of institution were unknown: A clear understanding of an institution's offerings and governance is essential for accurate categorization and analysis.
Administrative offices of institutions when the institution itself was counted separately: To avoid duplication and ensure each distinct educational entity is represented once, administrative headquarters were excluded if the primary operational institution was already included.
For public schools, driving distances were restricted to the state where the school was located: This methodological choice acknowledges the typical geographic scope of public institution attendance and funding, preventing the inclusion of out-of-state public institutions in the distance calculations for local market analysis.

Institutions that are required by the Department of Education to participate in Title IV federal student financial aid programs are mandated to report data to IPEDS. These institutions are listed as separate entities within the IPEDS database, ensuring their inclusion in the analysis if they meet the other criteria.

Sources and Acknowledgements

The comprehensive nature of this project is made possible through the diligent collection and integration of data from various reputable sources. The Higher Education Finance Team at Jain Family Institute is credited with producing this insightful analysis. The mapping and geographical data were provided by OpenStreetMap contributors, with data from the NYU Spatial Data Repository (2010) concerning "5-Digit ZIP Code Tabulation Areas (ZCTA5) United States 2010."

Population estimates are derived from the U.S. Census Bureau's American Community Survey (ACS) 5-year estimates (2012-2016), specifically Table B19013 for Median Household Income and Table S0101 for general population data. Geographic boundary data was sourced from the Census Bureau's TIGER/Lines ShapeFile (2018).

Crucially, the core educational data-institutional characteristics and enrollment figures-comes from the National Center for Education Statistics (NCES) within the U.S. Department of Education's Integrated Postsecondary Education Data System (IPEDS). Data from the 2016-17 Institutional Characteristics and 2017 12-Month Enrollment tables were utilized. All data was accessed and compiled through October and November of 2019.

tags: #united #states #education #map #overview