Table 5.

Endogeneity tests: regression results of the instrumental variables method and PSM method.

Variables	LDig as a tool variable		ADig_median as a tool variable		PSM
	Stage 1	Stage 2	Stage 1	Stage 2
	(1)	(2)	(3)	(4)	(5)
	Dig	tfp	Dig	tfp	tfp
LDig	0.7869***
	(32.174)
LDig_hat		0.1392***
		(6.7561)
ADig_median			0.6473***
			(13.3756)
ADig_hat				0.1449***
				(4.5341)
Dig					0.037***
					(3.639)
Size	0.4137	13.4511***	2.6309***	13.2765***	11.165***
	(1.3026)	(39.733)	(5.3059)	(40.186)	(12.392)
Age	− 0.0589**	− 0.102***	− 0.1677**	− 0.0758**	− 0.13
	(− 2.0023)	(− 3.3119)	(− 2.3726)	(− 2.1131)	(− 1.013)
Shrcr1	0.0014	0.0025**	0.001	0.0023**	0
	(1.5183)	(2.1671)	(0.7135)	(2.2573)	(0.136)
Lev	− 0.0289	0.261***	− 0.1429	0.3573***	0.276***
	(− 0.3094)	(2.8193)	(− 1.0752)	(4.2854)	(3.486)
Roa	0.3596	3.0582***	0.7564**	3.2551***	2.556***
	(1.2549)	(12.8689)	(2.2553)	(16.6125)	(14.359)
Board	− 0.1725*	0.076	− 0.645***	0.1405	− 0.018
	(− 1.6799)	(0.7721)	(− 3.4113)	(1.528)	(− 0.278)
Independent	0.0195	− 0.042	0.0727	− 0.0606**	− 0.146
	(0.5358)	(− 1.3036)	(1.1969)	(− 2.1167)	(− 0.789)
_cons	− 0.8517	− 32.59***	− 6.3237***	− 32.3729***	− 25.355***
	(− 0.9196)	(− 32.7977)	(− 4.2808)	(− 33.8388)	(− 9.436)
Year	Control	Control	Control	Control	Control
Firm	Control	Control	Control	Control	Control
N	1526	1526	2750	2750	2728
R2	0.6194	0.8082	0.2922	0.7876	0.642

T-statistics are shown in parentheses. ***, ** and * indicate 1%, 5% and 10% respectively.