How Does the Index Measure Health Security Preparedness?
The National Health Security Preparedness Index collects, aggregates and
measures existing state-level preparedness data from a wide variety of sources.
The Index then computes a range of key measures for all 50 states that, taken
together, display the broadest and most comprehensive national or state level
picture of health security available today. The Index is updated each year to
better reflect the multitude of factors that impact America’s health security
The 2016 National Health Security Preparedness Index uses an enhanced methodology that improves upon the validity and reliability of results offered in previous releases of the Index. The enhanced methodology ensures that individual measures do not have a disproportionate impact on the Index results due purely to their scaling and position within the Index, while also allowing Index results to be tracked and compared validly across years. Because of these changes in methodology, the 2016 Index results are not directly comparable to results from previous releases of the Index. However, the 2016 Index includes annual results for a three year time period spanning 2013 to 2015, allowing users to track progress over time.
Key Changes for 2016
- Normalization: Each individual measure is normalized to a standard ten-point scale using the min-max method that preserves the full distribution of each measure and prevents categorical measures from having a larger impact on Index results compared with continuous measures.
- Weighting: Each measure is assigned a weight based on expert panel ratings of how important the measure is to the capabilities represented in each Index domain and subdomain. These weights are used to combine individual measures into summary measures at the subdomain, domain, and overall level. This methodology ensures that more important measures receive more weight in the Index, and prevents measures from arbitrarily receiving more weight based purely on the number of measures included in each domain and subdomain.
- Missing values: Missing values for individual measures are estimated using a statistical imputation method that uses current and past values of multiple Index measures, along with state characteristics, to generate accurate estimates. This method greatly improves upon the accuracy of the imputations used in prior Index releases.
- Longitudinal comparisons: For the first time, the 2016 Index includes annual results for each of the years 2013 through 2015 using a standard methodology, allowing results to be trended and compared over time.
- Confidence intervals: For the first time, the 2016 Index estimates confidence intervals around each of the national summary measures. These intervals allow users to determine whether state results are significantly above, below, or in line with national norms.
- Streamlined Index content: The 2016 Index is constructed from a total of 134 individual measures, down from nearly 200 measures included in the 2014 Index release. Measures were eliminated from the 2016 Index if updated data were not collected at least every 3 years. Additionally, we used a series of measurement validity and reliability tests to weed out redundant measures and measures lacking a strong empirical association with the Index domain and subdomain areas. Validation results show that the streamlined 2016 Index performs just as well as larger previous versions of the Index in estimating state and national preparedness levels, while offering more precise estimates that facilitate comparisons across domains, geographic areas, and time periods.
Full details of the Index methodological approach for 2016 are available here.
The National Health Security Preparedness Index tracks the nation’s progress in preparing for, responding to, and recovering from disasters and other large-scale emergencies that pose risks to health and well-being in the United States. Because health security is a responsibility shared by many different stakeholders in government and society, the Index combines measures from multiple sources and perspectives to offer a broad view of the health protections in place for nation as a whole and for each U.S. state. Full details of the Index methodological approach for 2016 are available for download here.
Suggest New Measures
To continuously improve the Index, stakeholders are invited to recommend new measures for inclusion, to recommend changes to existing measure definitions and specifications, and to recommend deletion of existing measures from the Index.
Recommendations for new measures that reflect social, economic, and/or environmental dimensions of preparedness and resiliency are especially encouraged, as these constructs are currently under-represented in the Index structure. The Index gives priority to measures that can be constructed from existing, low-cost data sources such as surveys, records, registries, documents, images, sensors, or other automated monitoring systems. We are especially interested in measures that make use of novel electronic data sources such as data from web search engines, social media, satellite imagery, and commercial transactions. Measures that have been previously validated and that provide both national-level and state-level estimates of preparedness and resiliency are of primary interest. If you have suggested new measures to consider for future Index releases, Click here.