Methodology and Data Sources

The indicators

Twenty-three indicators of the existence or absence of peace were chosen by the panel of experts, which are divided into three broad categories: measures of ongoing domestic and international conflict, measures of safety and security in society and measures of militarization. All scores for each indicator have now been “banded”, either on a scale of 1-5 (for qualitative indicators) or 1-10 (for quantitative data, such as military expenditure or the jailed population, which have then been converted to a 1-5 scale for comparability when compiling the final index). Qualitative indicators in the index have been scored by the Economist Intelligence Unit’s extensive team of country analysts, and gaps in the quantitative data have been filled by estimates by the same team.

Indicators consisting of quantitative data such as military expenditure or jailed population have been measured on the basis of the distribution of values across all countries between the maximum and minimum values (we assume that the 144 countries measured for the Global Peace Index are a representative sample of all countries). Each of the indicator’s data set has been divided into ten bands based on the full range of the data set and a country’s corresponding score results in its position in the distribution. Each indicator’s range between the maximum and minimum values has now been anchored in time based on data collected for the 2008 Global Peace Index. This is a change to the measurement methodology used in previous versions of the GPI and a description is provided below. In order to make comparable and fair assessments over time, the 2009 methodology has been used to recalculate GPI 2008. All ranking and score changes between the 2009 GPI and 2008 GPI are on the basis of these enhanced measuring techniques. A detailed explanation of the scoring criteria used for each indicator is available in the Results Report.

Measures of ongoing domestic and international conflict

The Global Peace Index is intended as a review of the state of peace in nations over the past year, although many indicators are based on available data from the last two years. The panel of experts decided against including data reflecting a country’s longer-term historical experience of domestic and international conflict on the grounds that the GPI uses authoritative statistics on ongoing civil and trans-national wars collated by institutes such as the Uppsala Conflict Data Program and the International Peace Research Institute, Oslo. These, combined with two indicators scored by the Economist Intelligence Unit’s analysts, comprise five of the 23 indicators:
  • Number of external and internal conflicts fought: 2002-07
  • Estimated number of deaths from organized conflict (external)
  • Number of deaths from organized conflict (internal)
  • Level of organized conflict (internal)
  • Relations with neighbouring countries
Measures of societal safety and security

Ten of the indicators assess the levels of safety and security in a society (country), ranging from the perception of criminality in society, to the level of respect for human rights and the rate of homicides and violent crimes. Crime data is from the UN Office of Drugs and Crime. Five of these indicators have been scored by the Economist Intelligence Unit’s team of country analysts:
  • Perceptions of criminality in society
  • Number of displaced people as a percentage of the population
  • Political instability
  • Level of disrespect for human rights (Political Terror Scale)
  • Potential for terrorist acts
  • Number of homicides per 100,000 people
  • Level of violent crime
  • Likelihood of violent demonstrations
  • Number of jailed population per 100,000 people
  • Number of internal security officers and police per 100,000 people
Measures of militarization

Eight of the indicators are related to a country’s military build-up - reflecting the assertion that the level of militarization and access to weapons is directly linked to how at peace a country feels internationally. Comparable data are readily available from sources such as the International Institute of Strategic Studies (IISS):
  • Military expenditure as a percentage of GDP
  • Number of armed services personnel per 100,000 people
  • Volume of transfers (imports) of major conventional weapons per 100,000 people
  • Volume of transfers (exports) of major conventional weapons per 100,000 people
  • Funding for UN peacekeeping missions: outstanding contributions versus annual assessment to the budget of the current peacekeeping missions
  • Aggregate number of heavy weapons per 100,000 people
  • Ease of access to small arms and light weapons
  • Military capability/sophistication
Weighting the index

The panel of experts apportioned scores based on the relative importance of each of the indicators on a 1-5 scale. The consensus scores for each indicator are presented in the results report.

Two sub-component weighted indices were then calculated from the GPI group of indicators:
  1. a measure of how at peace internally a country is;
  2. a measure of how at peace externally a country is (its state of peace beyond its borders).
The overall composite score and index was then formulated by applying a weight of 60% to the measure of internal peace and 40% for external peace. The heavier weight applied to internal peace was agreed within the panel of experts, following robust debate. The decision was based on the innovative notion that a greater level of internal peace is likely to lead to, or at least correlate with, lower external conflict.

Changes to the methodology for 2009

The international panel of experts that oversees the compilation of the Global Peace Index chose to include five additional countries in the 2009 edition: Burundi, Georgia, Guyana, Montenegro and Nepal. Hong Kong was dropped in response to queries about its status as a special administrative region of the People’s Republic of China. While Hong Kong maintains a high degree of autonomy, foreign affairs and defence are the responsibility of China’s authorities in Beijing. This brings the total number of countries covered to 144, encompassing almost 99% of the world’s population and over 87% of the planet’s land mass.

A further change involved the removal of two indicators featured in the Global Peace Indexes of 2007 and 2008: the measures of UN and non-UN deployments. The former was dropped because it was generally felt that it was not a sufficiently accurate measure of a commitment from countries to UN peacekeeping missions. In the 2009 GPI the UN deployments indicator has been replaced with a measure of financial support to UN peacekeeping missions as all UN member states share the cost of mounting these operations. The indicator calculates the percentage of countries’ “outstanding contributions versus annual assessment to the budget of the current peacekeeping missions” (see the Results Report for a full definition).

The indicator of Non-UN deployments was initially included on the assumption that a country deploying troops overseas cannot be considered free of violence. However, members of the panel of experts acknowledged that the indicator is potentially ambiguous - should the deployment of troops overseas, whose mission is to prevent genocide in a foreign country, be recorded as a “negative” indicator in the GPI? In order to avoid making such judgements, the consensus view was to remove the indicator.

The two previous editions of the Global Peace Index have been compiled using a combination of “raw” quantitative scores that were “normalized” and scores (mainly qualitative) that were banded using a scale of 1-5. The compilers have observed that the use of raw scores contributed to the volatility of the index, so, following discussion with the overseeing panel of experts, it was decided this year to place all of the scores across the 23 indicators in bands, on either a scale of 1-5 or 1-10.

In order to make appropriate analysis of year-on-year changes to scores and rankings of the GPI, the Economist Intelligence Unit analysts have used the amended set of indicators and weights as decided upon by the panel of experts to construct a revised index and set of rankings for the 2008 GPI. All discussions of changes in rankings and scores refer to these new methodologies. For more details, see Annex B of the Results Report.