What is neighborhood vulnerability?
The concept of social vulnerability stems from disaster mitigation research and focuses on the socioeconomic characteristics of households in neighborhoods that might determine the collective ability to prepare for and cope with a “hazard event” such as natural, public health, or economic disaster (Highfield et al., 2016). Particularly vulnerable areas may not only be disproportionately affected by the disaster itself, but also may not be able achieve long-term recovery (Martin, 2015).
Study methodology
This phase of the City of Tucson/Pima County housing study project was modeled after the Austin Uprooted study, a peer-reviewed and generally accepted methodology for measuring neighborhood vulnerability. The preceding maps were built after calculating a composite score of five relevant indicators to determine whether a given census tract falls above or below the mean measurement of the metropolitan area. While there are certainly more than five indicators that may signal neighborhood vulnerability, many of those indicators are overlapping and may dilute findings as a greater number of indicators are added. We have found that these particular American Community Survey indicators are more dependable than most at the granular tract level.
The five vulnerability factors
1. Percent of residents that identify as anything other than “non-Hispanic white alone”
A 2014 Pew Research Center study found the post-Great Recession median wealth of white households to be 13 times that of black households and 10 times the wealth of Hispanic households. We also know that density of non-white residents in low-income communities have compounding wealth effects, as well as educational and other socioeconomic effects.
2. Percent of households who rent, rather than own, their homes
In terms of housing status, renters as a group are more vulnerable to hazard events that might shock a community. In the event of natural disaster, renters are generally not insured to the point of substitute housing. In the event of economic disaster, renters could be displaced by their own economic hardship or that of a landlord who might be forced to sell a property. See this Making Action Possible (MAP) dashboard article for more information about how renters fare in housing affordability in Tucson.
3. Percent of residents aged 25 and over who lack a four-year bachelor’s degree or higher
Workers lacking a college degree are more likely to be unemployed, or to be employed in lower-wage, part-time, or seasonal jobs. This employment situation makes these workers particularly vulnerable to mass job loss and other economic events. The MAP dashboard has a deeper analysis of educational attainment in the Tucson area.
4. Percent of households with incomes below 80% of Area Median Income (determined by HUD)
Acknowledging that income is not wealth, households with incomes below median income are known to be more cost-burdened, thus sensitive to variable housing costs and other economic shocks. The MAP dashboard has a detailed analysis of housing cost burden phenomenon.
5. Share of children that live in households below the official poverty line
Household type plays a role in vulnerability, particularly when coupled with other indicators such as low-income or lack of college degree. One point of concern is whether families most vulnerable to displacement have difficulty finding alternative housing, which is more often the case in families with children. The MAP dashboard also has a detailed analysis of poverty rates in Tucson, including in families with children.
The composite score
A vulnerable census tract meets two conditions: 1. it has three or more vulnerable factors, and 2. it has a composite score greater than zero.
Each of the five vulnerability factors was evaluated individually on whether its measurement fell above or below the mean of the metropolitan statistical area (Pima County). When a factor is above the mean, the tract is considered vulnerable for that factor. Each tract is then evaluated based on its number of vulnerable factors; if a tract has three or more vulnerable factors, it meets the first condition for vulnerability. Finally, the five factor scores are averaged across each tract for a composite score, with each factor weighted equally in the composite score. A tract is considered vulnerable when the composite score is more than zero; the greater the composite score is above zero, the greater the magnitude of vulnerability in that tract.
