The HVRI Social Vulnerability Index (SoVI), developed by the Hazards Vulnerability and Resilience Institute (HVRI) at the University of South Carolina, measures the social vulnerability of U.S. counties to environmental hazards. mySidewalk calculates this index by applying HVRI's methodology to the latest American Community Survey (ACS) data.
What is the HVRI Social Vulnerability Index?
The SoVI is a comparative metric designed to highlight differences in social vulnerability across U.S. counties. It helps identify areas with uneven preparedness and response capacity, guiding policymakers on where resources can be most effectively allocated to reduce vulnerability. The index also plays a crucial role in assessing differential recovery after disasters.
Data Summary: What Does SoVI Measure?
The SoVI summarizes the following key data points:
Housing and Demographics: Total renter-occupied housing, median age, people in nursing facilities, dependent populations (age >65 or <5), total female population.
Economic Indicators: Unemployment rate, per capita income, households with social security income, income over $200,000, excessive housing costs (over 30% of income).
Health and Education: People without high school diplomas, people without health insurance, individuals with disabilities, people below the poverty level.
Other Socioeconomic Factors: Mobile homes, families with single female householder, households without internet, service employment, and more.
For a full list of the data summarized by SoVI, visit the HVRI SoVI Data Resource.
How Is the HVRI SoVI Built?
mySidewalk builds the SoVI index through the following steps:
Data Collection: Raw data is gathered from the most recent U.S. Census American Community Survey (ACS) 5-Year Sample.
Data Transformation: Raw count data is converted into ratios (e.g., converting the total number of females into females per capita).
Handling Missing Data: Missing values are inferred from surrounding geographies. When this is not possible, observations (e.g., Tracts or Counties) are excluded.
Z-Score Standardization: The data is standardized to ensure comparability across indicators.
Principal Components Analysis (PCA): The standardized data undergoes PCA with Varimax rotation, resulting in principal components that are summed (without weighting) to generate a raw SoVI score.
Percentile Ranking: The scores are then ranked, with values closer to 1 indicating higher social vulnerability and values closer to 0 indicating lower vulnerability.
Geographies Available
The HVRI SoVI index is available for the following geographic levels:
Census Tract
Zip Code
Place
County Subdivision
Unified School District
State House District
State Senate District
County
Metropolitan Planning Organization (MPO)
Metropolitan and Micropolitan Areas
U.S. Congressional District
State
Each geography is calculated independently.
Citations
Cutter, Susan L., Bryan J. Boruff, and W. Lynn Shirley. "Social Vulnerability to Environmental Hazards." Social Science Quarterly, vol. 84, no. 2, 2003, pp. 242-261.