Data coverage 1. Geography Across all metrics, the barometer aims to collect global data. In most cases, an aggregate global weighted average is available. When a global weighted average is not available, the most comprehensive data is used – such as Organisation for Economic Co- operation and Development (OECD) member countries, or a sample set of countries where data is available for all years. 2. Years While the barometer measures cooperation from 2012 through 2023, some metrics do not have data for all years. All metrics have 2020 data to ensure the indexed trendline can be calculated. Index calculation To evaluate global cooperation fairly and compare trendlines of the action and outcome metrics across the five pillars, the global cooperation barometer applies the following methodology: 1. Indexed trendlines Data from 2020 serves as the base year to develop comparable trendlines, with all values in 2020 equal to one (2020 = 1). This base- year standardization is the basis of the score calculation, enabling a uniform reference point for all metrics and comparability, despite different units and datasets. 2. Data normalization Where possible, metrics are normalized to ensure that trendlines can be assessed independently of the effects of economic growth or population changes. For example, trade, capital and other financial flows are normalized to global GDP (gross domestic product) while migration metrics are normalized to global population levels. 3. Weighting Each pillar comprises two indices: an action index and an outcome index. To arrive at each, the metrics within are weighted equally (i.e. the action index is a simple average of metrics measuring cooperative actions). The overall index for a pillar is calculated as an average of the action and outcome metrics. Aggregate indices across pillars are also calculated as a simple average of pillar indices (i.e. equal weighting across pillars). 5 The Global Cooperation Barometer 2025 Second Edition