VIMS SoVI: Following other social vulnerability indexes, including the SoVI® developed by the Hazards & Vulnerability Research Institute at the University of South Carolina, this vulnerability index is based on a principal component analysis (PCA). PCA is a statistical technique that takes as its input a matrix of interrelated socioeconomic variables – in this case those considered to measure various dimensions of social vulnerability – and creates a new set of orthogonal principal components that extract the important variation the underlying input data while reducing the noise and redundancy in the data. After conducting the PCA, the researcher combines the newly created component variables into a composite index that provides a single value for each observation in the dataset, in this case a social vulnerability score. The utility of a PCA-based index is that it encapsulates a lot of information in an easily consumed form and individual observations can be ranked relative to each other. This update uses data from the 2015-2019 American Community Survey at the census block group level where available and at the census tract level where block group data is not available. It uses the following percent of population variables: income (per capita), Black or African American, Hispanic, Native American, over 65, unemployed, poverty status, no high school degree, group quarters (i.e. nursing homes and prisons), female labor force, female households, and social security. The vulnerability indices generated depend on the variables included in the PCA as well as the geographic area of the study and the component selection and weighting criteria. Thus this vulnerability index will not necessarily match the vulnerability indices created by other researchers. See complete documentation here. 

ATSDR: The CDC\ATSDR Social Vulnerability Index (SVI) is a tool, created by the Geospatial Research, Analysis and Services Program (GRASP), to help public health officials and emergency response planners identify and map the communities that will most likely need support before, during, and after a hazardous event. The tract-level SVI shows the relative vulnerability of the population of every U.S. Census tract. The county-level SVI shows the relative vulnerability of every U.S. county population. The SVI ranks tracts (or counties) on 16 social factors, described in detail in the documentation. The tract (or county) rankings for individual factors are further grouped into four related themes. Thus each enumeration unit receives a ranking for each Census variable and for each of the four themes, as well as an overall ranking. See complete documentation here. For additional questions, contact the SVI Lead at svi_coordinator@cdc.gov.