What do the numbers "mean?"  That is, if Uganda's value is 0.65, does that mean that on a scale of 1-4 (1 being the least) that Uganda is very unlikely to be exposed to the 6 hazards you describe?

Below is the description of the variable, which is also available from http://sedac.ciesin.columbia.edu/es/esi/c_variableprofiles.pdf.  The methodology explains the scale – but essentially, the score is an index, but for interpretation purposes, a score of  2 would mean that the equivalent of twice the total population of the country is exposed to two or more potentially high impact hazards.  A score of  0.65 means that roughly two-thirds of the population of Uganda is exposed to 1 or more of the hazards listed.

Variable #: 45 Code: DISEXP Reference Year: 2005
Description: Environmental Hazard Exposure Index
Units: An index of population-weighted exposure to high levels of environmentally-related natural hazards.
Source: The World Bank.
Logic:  Vulnerability to natural disasters is a function of the exposure to hazards (how often and how severe they are), the sensitivity to such hazards (how big the linkages are to social systems), and the resilience within a society to hazard impacts. This measure provides a useful proxy of the exposure term.

Methodology: To calculate the environmental hazard exposure index, data from Dilley et al. were used. Data on exposure to landslides, droughts, cyclones and floods were put into a consistent GIS database. The world’s land area was classified into degrees of exposure to these four hazards. Those grid cells falling into the highest three deciles of exposure were flagged. The number of high-exposure hazards was summed for each grid cell. The values range from 0-4. The resulting gridded data set was then overlaid with a gridded population data set for the year 2000. Each person was assigned a score equal to the number of high-exposure hazards identified in that grid cell. We calculated the sum of personal exposure scores, and divided by the total population, by country. The theoretically possible range was 0-4. The actual index ranged from 0 to 2.04. 

Environmental Sustainability Index

  1. Could you please let me know if there is any link between the ESI and Corporate Triple Bottom Line (TBL) Reporting? Alternatively, would you regard the ESI as a proxy for national TBL reporting?
  2. Could you please tell me how and with what kind of weighting the ecological footprint has been factored into the 2002 ESI?
  3. How often will the ESI be updated?
  4. I am currently evaluating different indices of sustainable development and came across the 2002 ESI profile for Belgium (Annex 5, p. 93). Could you explain why air quality is above average when the emission of air pollutants ('reducing air pollution') is extremely high?
  5. I am looking for the ESI reports for 2003 and 2004.   Is the ESI available for these years?
  6. I have read with interest the Environmental Sustainability Index that has been developed at Columbia University. For my Master's Thesis I am looking at developing a framework for measuring sustainability. I am particularly interested in measuring differences at the regional/state level. Would you see the application of the Environmental Sustainability Index at the state level as effective? Would it need to be modified or could it serve as a useful comparison for states to national achievements.
  7. I read the 2002 Environmental Sustainability Index (ESI) where Uruguay is on 6th place. Its component score ranks range from 19th to 35th. Are other countries much more variable so their high ranking components are counterbalanced by low ranking components? I want to know which variables where the most important to put Uruguay in such a good place in the world list?
  8. I would like to do a time series analysis to look at the change in environmental sustainability in specific countries, but I am unsure if the data for your 2001 and 2002 ESI is different, or whether the 2002 ESI is just the result of fine-tuning definitions and categories.
  9. In reviewing the latest statistics on environmental sustainability from your website, I noted that the Faroe Islands was not listed. Could you please advise me on the criteria regarding who is included in the 2002 ESI rankings?
  10. Is it possible to do a time series analysis on the ESIs?
  11. We just finished reading Esty and Cornelius' Environmental Performance Measurement: The Global Report 2001-2002, where the ESI was discussed. We also looked at the 2002 ESI online. We are finding that the methodology sections (both in the book and online) are insufficient to allow us to replicate the rankings. We are interested in seeing how the rankings change if we impute our own weighting schemes, but to do so requires that we understand how they were done in the first place. So, here are our questions: 1. How were the z-scores for each of the variables converted to a percentile? 2. How were the percentiles converted to the indicator? Was this a sum of all the percentiles, an average of the percentiles, or something different? 3. How were the indicators compiled to create the overall ESI? 4. Were missing values included in all the above computations or were values imputed in the above prior to the computation of z-scores?
  12. We would very much appreciate you informing us on how you base your calculations on the profitability on water, or possibly its quality.
  13. What do the numbers "mean?"  That is, if Uganda's value is 0.65, does that mean that on a scale of 1-4 (1 being the least) that Uganda is very unlikely to be exposed to the 6 hazards you describe?
  14. What does the "z" score for a peer group mean?
  15. What does the Peer Group ESI mean?
  16. What is the most recent version of the ESI?
  17. What is the reason that an EPI was established as a complement to the ESI?
  18. What were the data sources used for the 2001 ESI?
  19. Where can I find more information about the ESI 2002 methodology?

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