Fig. 3: Study methodology across ORO types.

The height of each bar is proportional to the percent contribution of each method type towards the total number of publications predicted relevant for each ORO type (labelled in black numbers on the top of each bar). The combined percent contribution of both types of empirical studies is labelled in green on the top of each bar. If an article is not classified as relevant for any of the coded method types, it is classified as ‘other’.