Calculation SSI

1. Selection of countries

The Sustainable Society Index has been developed for as many countries as possible. This offers the option of comparison between countries using various viewpoints: neighbouring countries, more or less similar countries, regional comparisons, comparisons between rich countries like the OECD members, comparison between North and South, etc.

However, 43 of the existing 194 countries had to be left out due to a lack of data. This concerns some bigger countries, like Afghanistan , Djibouti , Eritrea , Somalia and Surinam and most small island states. The SSI has been calculated for 151 countries, one more than for the SSI-2006, Montenegro .

2. Data

Data from public sources, i.e. from scientific institutes and international organizations, were collected for the 151 selected countries. If data of a certain indicator were missing for a country, the average of data of this indicator from comparable countries (according to the classification of clusters by ESI, Environmental Sustainability Index) was used.

3. Sustainability value and scoring system of the indicators

* Sustainability value

The sustainability value of each of the 22 indicators is the value at which full sustainability is achieved. This is the final target for an indicator. It is remarked that the sustainability value cannot always be determined objectively, nor will it in all cases be constant over time. Full sustainability will be achieved when a country achieves the sustainability value for each indicator. The difference between the current value of an indicator and the sustainability value gives the distance to sustainability.

For a number of indicators, the sustainability value can be determined objectively. For instance, the number of undernourished people has to be 0 (indicator 2), or the percentage of people with access to safe drinking water has to be 100 (indicator 3). This reasoning applies for indicators 2, 3, 4, 5, 6, 15, 17 and 22. However, some might question why the gender equality has to be 1. So even in this rather obvious case, some subjectivity is included.

For the remaining indicators the sustainability value is less obvious and probably cannot be determined in an objective manner. When is population growth sustainable? If the number of inhabitants stays constant? Or only when it declines? And if so, at which percentage does it have to decline to be sustainable? Or when is income inequality sustainable? Moreover, the sustainability value of an indicator may vary over time. For instance population growth: currently our planet seems to be rather overpopulated. However, it can very well be that our view on this issue will change in the future.

For indicators 18, 20 and 21 an educated guess of the sustainability value can be made.

If even an educated guess is not reasonably possible, the highest value (best case) of the 151 assessed countries for that indicator is considered the sustainability value, while the lowest value (worst case) is assumed to represent no sustainability at all.

* Scoring system

All indicators (and subsequently the categories and the overall index) have been allocated a score on the scale from 0 to 10. An indicator scores a 10 in the case of 100% sustainability. If there is no sustainability at all, the score for the indicator is 0.

The transformation from raw data to indicator scores has been done by standardization, apart from indicators 11, 13, 14 and 18. For these indicators, more complex formulas have been used, in line with the characteristics of the indicator. In the cases where the sustainability value is based on an educated guess, the calculated maximum score is often slightly lower than 10, depending on the chosen formula, so the calculation does not have to be adjusted every time new maximum raw data become available. The same applies for the calculated minimum scores.

4. Calculation of indicators

A detailed description of the calculation of each indicator is given in the publication Sustainable Society Index 2008. The related pages can be downloaded here.

5. Calculation of categories

The 22 indicators have been aggregated into the 5 categories, in order to show at a glance the results of the 5 main themes of the SSI.

One may consider one indicator to be more important for achieving sustainability than another. This may certainly be the case but due to a lack of a scientific basis for the attribution of different weights to the indicators, each indicator has received the same weight for the aggregation into categories.

6. Calculation of the overall index

The same procedure, for the same reason, which has been followed for calculating the categories, could be applied for the aggregation of the five categories into one figure for the overall index. However, examining the impact of each category on the sustainability of a particular country and of the world at large, it is obvious that quality of life has its main effects - though certainly not all - within a country, whereas sustainability also has serious effects on other countries and on the world at large. Therefore, the three categories with emphasis on quality of life received a weight 1/7 th ; the two categories with emphasis on sustainability received a double weight, 2/7 th . As yet there is no sound scientific theory to support this. However, this has been done since it seems to better reflect the relative importance of the latter two categories.