“…Feige (1979Feige ( , 1990 argued that unofficial economy includes activities which are not reported and unable to be measured directly. Ihrig and Moe (2004) were of the view that an unofficial economy may include a legal production industry but this industry is not appropriate to be in existence in the economy or with the government's regulations. In addition, Frey and Pommerehne (1984); Loayza (1996) ;Johnson, Kaufmann and Shleifer (1997) ;Johnson, Kaufmann và Zoido-Lobaton (1998; Thomas (1999);Fleming (2000); Enste (2000, 2002); Dell'Anno and Schneider (2003); Schneider (2005Schneider ( , 2006Schneider ( , 2007Schneider ( , 2010Schneider ( , 2012Schneider ( , 2013 and many other studies have also adopted a very similar definition of the unofficial economy.…”