Table 2.

Quality index scoring based on Newcastle–Ottawa Scale (NOS).

Source	Selection (4 Max)	Comparability (1 Max)	Outcome (3 Max)	Overall Rating (8 Max)
Schlosser S [10] (2020)	2	1	2	5
Ciftciler R [21] (2019)	3	1	3	7
Li S [32] (2019)	3	1	2	6
Bryk S [42] (2018)	3	1	2	6
Kwon W [43] (2018)	3	1	3	7
Corso G [44] (2018)	3	1	2	7
Joung J [45] (2018)	3	1	3	7
Kumar V [46] (2018)	3	1	2	6
Chen T [47] (2017)	3	1	3	7
Sud A [11] (2017)	3	1	2	6
Kanninen T [12] (2017)	3	1	3	7
Lococo F [13] (2017)	3	1	3	7
Liao Z [14] (2017)	3	1	3	7
Liu Y [15] (2017)	3	1	2	6
Murray K [16] (2016)	3	1	3	7
Krilaviciute A [17] (2016)	3	1	3	7
Silverman B [18] (2016)	2	1	3	6
Marcheselli, R [19] (2015)	4	1	3	8
An J [5] (2015)	2	1	3	6
Michaelson E [20] (2014)	3	1	3	7
Koivisto-Korander R [22] (2012)	4	1	3	8
Antonelli A [23] (2012)	3	1	3	7
Tabuchi T [7] (2012)	3	1	2	6
Yadav B [24] (2009)	3	1	3	7
Lee K [25] (2008)	3	1	3	7
Kirova Y [26] (2008)	3	1	3	7
Mellemkjaer L [27] (2006)	3	1	3	7
Sadetzki S [28] (2003)	2	1	3	6
Adjadj É [29] (2003)	3	1	3	7
Tanaka H [30] (2001)	3	1	3	7
Huang J [31] (2001)	3	1	3	7
Li C [33] (2000)	3	1	2	6
Friedman, G [34] (2000)	3	1	3	7
McCredie M [35] (1997)	3	1	3	7
Volk N [36] (1997)	4	1	3	8
Lindelöf B [37] (1991)	3	1	3	7
Gutman M [38] (1991)	3	1	3	7
Boice J [39] (1988)	3	1	3	7
Murakami R [40] (1987)	4	1	2	7
Ron E [41] (1984)	3	1	2	6