“…Within these studies, since Färe et al's (1989) there have been many works of this nature which divide the outputs into two categories -the desirable and the undesirable -among which are those of Dyckhoff and Allen (2001), Ramanathan (2002), Lansink and Bezlepkin (2003), Korhonen and Luptacik (2004), Liang et al, (2004), Triantis and Otis (2004), Zaim (2004), Picazo-Tadeo et al, (2005), Kumar (2006) and Pasurka (2006). There have also been numerous works in recent years which have followed this plan - Fare and Groskopf (2010), Liu et al, (2010), Zhou et al, (2010), Sahoo et al, (2011), Wang et al, (2014, Kounetas (2015), Sueyoshi and Goto (2015), and Zhang et al, (2015).…”