This thesis evaluates and develops a method for studying the occurrence of cascading effects between critical infrastructures. The thesis also analyzes how the results of previous research using the method may have been affected by certain aspects of the method. Applying different inclusion thresholds and exploring how material could be gathered differently, the thesis provides some tentative answers to the value of using newspaper articles when studying cascading effects. In addition, the thesis offers recommendations for future research and policy on the protection of critical infrastructures.