study	t_thr	n1	n2	bis_grade	
Wang2018	2.000	33	35	64.57	
Wang2016	2.024	20	20	66.90	
Ge2017	3.460	33	29	52.41	
Zhai2015	2.030	15	22	66.45	
Qiu2014	2.403	30	30	71.63	
Hung2020	3.496	19	34	68.5	
