“…Although Kromann et al (2011) argue that the best variable reflecting technological changes in the economy is R&D expenditures, the patents, as Kortum (1997) suggests, is the main technological variable reflecting the important aspects of the technological process and, presumably, "correlating with the immeasurable dimensions of technological change." However, according to Feldmann (2013), Dernis and Khan (2004), the following limitations on the calculation of patents under their registration at the national patent office can be pointed out: first, the registration of patents in one office varies greatly according to their technical and economic significance; secondly, it is difficult to compare them internationally, since they are affected by local preferences and geographic location. For these reasons, the number of triadic patent families per one million inhabitants (independent/exogenous variable) which avoids these limitations is used in the research as the main output indicator of technological innovation.…”