Correlation is a statistical measure that describes the relationship between two indices. A positive correlation means that both indices are increasing or decreasing in parallel. A negative correlation indicates that when a country’s performance improves on one index it worsens on the other. The relation is strong if the correlation coefficient is greater than 0.7 (smaller than -0.7). it is milled if the coefficient is between 0.4 and 0.7 (or -0.7 and -0.4). Correlation coefficients, that appear on the table, can be used to assess how performances across indices tend to be linked to each other.

However, correlation must not be confused with causality. If two indices/indicators are correlated, it does not imply that one index/indicator causes the changes in another one. Correlation only assesses relationships between indices/indicators, and different factors may lead to the relationships. Causation may be a reason for the correlation, but it is not the only possible explanation.