  We inspect a possible clustering structure of the corruption perception among
134 countries. Using the average linkage clustering, we uncover a well-defined
hierarchy in the relationships among countries. Four main clusters are
identified and they suggest that countries worldwide can be quite well
separated according to their perception of corruption. Moreover, we find a
strong connection between corruption levels and a stage of development inside
the clusters. The ranking of countries according to their corruption perfectly
copies the ranking according to the economic performance measured by the gross
domestic product per capita of the member states. To the best of our knowledge,
this study is the first one to present an application of hierarchical and
clustering methods to the specific case of corruption.
