Table 5. Estimation result (dependent variable: annual R&D investment per stock)

Specification	GMM-SYS		Robust check
			Fixed effect OLS		Pooled OLS
	Spec. 1	Spec. 2	Spec. 3	Spec. 4.	Spec. 5	Spec. 6.
λ1Ri,t−1Ci,t−2	–0.001*** (0.000)	–0.001*** (0.000)	–0.001*** (0.000)	–0.001*** (0.000)	–0.001*** (0.000)	–0.001*** (0.000)
γ2Δyi,t	0.083*** (0.028)	0.079*** (0.027)	0.079** (0.030)	0.076*** (0.030)	0.110*** (0.026)	0.105*** (0.025)
γ3Δyi,t-1	0.094*** (0.025)	0.100*** (0.025)	0.103*** (0.025)	0.107*** (0.025)	0.089*** (0.025)	0.098*** (0.024)
γ4 (ci,t-1 − yi,t-2	–0.198*** (0.029)	–0.196*** (0.029)	–0.276*** (0.043)	–0.273*** (0.043)	–0.175*** (0.029)	–0.173*** (0.029)
γ5yi,t-2	–0.118*** (0.021)	–0.111*** (0.021)	–0.168*** (0.030)	–0.161*** (0.030)	–0.101*** (0.019)	–0.093*** (0.019)
ϕ1Zombie statusi,tCi,t−1	5,158.9*** (468.97)	5,084.6** (468.56)	5,613.1*** (462.81)	5,503.0*** (442.04)	5,649.9** (460.71)	5,542.9** (433.46)
ϕ2Zombiei,t×ILZSiCi,t−1	-	149,409.3** (60,078.25)	-	139,443.4** (65,582.93)	-	155,759.3** (64,433.88)
Constant	0.000*** (0.000)	1.832*** (0.311)	2.492*** (0.427)	2.366*** (0.431)	1.728*** (0.317)	1.576*** (0.321)
Firm fixed	Yes	Yes	Yes	Yes	No	No
Tech. field fixed1)	-	-	-	-	Yes	Yes
Year fixed	Yes	Yes	Yes	Yes	Yes	Yes
Observations	2,981	2,981	2,981	2,981	2,3372)	2,337
R-squared	-	-	0.114	0.118	0.130	0.139
Number of firms	704	704	704	704	-	-
Number of instruments	21	22	-	-	-	-
F-statistic	264.28	190.32	1,752.65	3,728.93	84.10	201.35
P (F-statistic)	0.000	0.000	0.000	0.000	0.000	0.0000
AR test (p-val) 1st order	0.109	0.106	-	-	-	-
2nd order	0.558	0.599	-	-	-	-
Hansen J test (p-val)	0.087	0.091	-	-	-	-

are statistical significance at 1%,
5%,
10% respectively; standard errors are also reported in parentheses; p-values are reported for AR test and Hansen J test.
Tech. field includes the followings: 1 (machine), 2 (electronics), 3 (information technology), 4 (chemical), 5 (bio), 6 (energy), 7 (knowledge service), 8 (ceramics).
In the pooled OLS estimation, the technology field is newly added unlike GMM-SYS and Fixed effect OLS estimation. Some missing data in technology field make difference in the number of total observations. R&D, research and development; GMM-SYS, Generalized Method of Moments System; OLS, ordinary least squares; ILZS, industry with lower zombie share; AR, auto-regressive.