Table 9 Analytical result of single subject research according to qualitative evaluation index

n	Authors (Year)	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22
1	Song et al. (2018)	2	2	2	1	0	2	2	2	1	0	2	2	2	1	2	1	2	2	2	1	2	2
2	Song & Paik (2017)	2	2	1	1	0	2	2	0	0	0	1	2	0	1	1	1	0	1	2	1	2	2
3	Kim et al (2017)	2	2	1	2	1	2	2	0	0	0	1	2	0	1	1	1	0	1	2	1	2	2
4	Ryu & Park (2022)	1	1	2	2	2	1	2	1	2	1	2	1	0	2	2	2	2	2	2	2	2	2
5	Juyeon & Hwang (2020)	1	2	1	1	1	2	2	2	2	1	2	0	0	2	1	1	1	1	2	1	2	2
6	Paik, Park, & Lee (2019)	2	2	2	2	2	2	2	2	1	2	2	2	0	2	1	1	1	1	2	1	2	2
7	Boo & Paik (2015)	2	1	2	2	0	2	2	0	0	0	2	2	1	2	2	1	0	2	2	2	2	2
8	Kang, Kim, & Son (2022)	1	2	2	2	2	2	2	1	1	1	1	0	0	2	1	1	2	1	2	1	2	1
9	Yoo & Lee (2016)	2	2	1	0	0	2	2	2	2	0	2	1	0	2	2	1	2	2	2	2	1	2
10	Kang et al. (2024)	1	2	2	2	2	2	2	2	1	1	2	1	0	2	1	1	2	2	2	1	2	2
11	Lee & Hong (2022)	2	2	2	2	2	2	2	2	2	1	1	2	2	1	1	2	1	2	1	2	2	2
12	Kim & Choi (2018)	2	2	2	2	2	2	2	0	0	0	2	1	2	2	2	2	0	2	2	2	2	2
13	Park & Lee (2018)	1	2	1	1	2	1	1	0	0	0	1	0	0	2	1	1	0	1	2	1	0	2
14	Lee & Paik (2023)	2	2	2	1	2	2	2	2	2	1	2	1	2	2	2	2	2	2	2	1	2	2
15	Lim et al. (2015)	2	2	2	2	2	2	2	0	0	0	2	2	0	2	1	1	2	2	2	1	2	1