Empirical Analysis of Supplier Inefficient Investment at Customer Risks Based on Supply Chain Data

Table 8

Robustness test.

Regression model	VOL_EBIT		Volatility of five-year ROA
	InvestEfft + 1	UnderInvestt + 1	InvestEfft + 1	UnderInvestt + 1
	(1)	(2)	(3)	(4)
khRiskt	0.045	0.074	0.042	0.073
	(1.729)	(2.184)	(1.657)	(2.040)
Sizet	−0.010	−0.021	-0.008	−0.021
	(−5.231)	(−6.932)	(−3.821)	(−5.358)
Levt	0.011	0.004	0.014	≥-0.001
	(0.949)	(0.273)	(1.155)	(−0.007)
Casht	0.029	0.053	0.018	0.054
	(2.177)	(3.309)	(1.127)	(2.345)
Aget	0.006	0.004	0.005	0.005
	(1.236)	(0.794)	(1.031)	(0.972)
Ocft	0.018	−0.037	0.020	−0.023
	(0.749)	(−1.311)	(0.782)	(−0.699)
Tact	−0.009	−0.003	−0.007	−0.002
	(−1.950)	(−0.485)	(−1.273)	(-0.366)
Sharet	0.090	−0.077	0.067	−0.059
	(1.408)	(−0.818)	(1.065)	(-0.604)
ROAt	0.073	0.073	0.074	0.044
	(2.299)	(1.869)	(2.001)	(0.944)
khSizet	0.002	−0.001	≥−0.001	−0.001
	(1.716)	(−0.489)	(−0.032)	(−0.567)
khLevt	0.009	0.020	−0.001	0.011
	(0.765)	(1.127)	(−0.090)	(0.632)
khAget	−0.001	−0.001	0.003	−0.002
	(−0.202)	(−0.158)	(0.624)	(−0.428)
khOcft	−0.014	−0.014	−0.023	−0.031
	(−0.599)	(−0.488)	(−0.970)	(−0.961)
Year	Control	Control	Control	Control
Industry	Control	Control	Control	Control
N	901	419	796	345
R-squared	0.141	0.305	0.095	0.242

Symbols , , and represent significance levels of 1%, 5%, and 10%, respectively.