“…There is no uniform DOI indicator in the existing literature. Lee and Kwok (1988) state that there is no generally accepted single DOI indicator and some DOI indexes emphasize structural characteristics: i.e., the number of countries in which the firm has subsidiaries (Burgman, 1996), or the number of its foreign subsidiaries ( Akhtar, 2005;Jouida & Hellara, 2018;Park, Suh & Yenug, 2013), while some DOI indexes focus on performance characteristics, i.e., the ratio of foreign sales to total sales (FSTS) (Aoun & Heshmati, 2008;Reeb, Kwok & Baek, 1998;Singh & Nejadmalayeri, 2004), or the ratio of foreign assets to total assets (Reeb, Kwok & Baek, 1998). In terms of international diversity indicators, Jouida and Hellara (2018) apply one minus the Herfindahl Hirschman Index (HHI) of foreign assets to total assets concentration as DOI index and Jamg (2017) uses one minus the HHI foreign sales to total sales concentration as a proxy of DOI, or geographic diversification (GD) index.…”