MIT Press

Table 8.

Regression results from the Total OA Articles hurdle models for Natural Resources and Conservation, Physical and Mathematical Sciences, and Social and Behavioral Sciences, showing the count data component (Total OA articles > 0) and the zero count component (Total OA articles = 0)

	Nat. Res. & Conservation				Phys. & Math. Sci.				Soc. & Behav. Sci.
	β	Sig.	e^β	Std. Err.	β	Sig.	e^β	Std. Err.	β	Sig.	e^β	Std. Err.
	Positive Count Component				Positive Count Component				Positive Count Component
Gender is Male	0.011		1.011	0.026	0.042	**	1.043	0.015	0.016		1.017	0.015
Institution is Public	−0.071	*	0.932	0.033	−0.099	***	0.906	0.014	−0.060	***	0.942	0.016
Institution is AAU Member	0.106	***	1.112	0.024	0.287	***	1.332	0.013	0.219	***	1.245	0.015
Years Since Degree	−0.004	**	0.996	0.001	−0.005	***	0.995	0.001	0.003	**	1.003	0.001
Professorial Rank	0.023		1.024	0.021	0.098	***	1.103	0.011	−0.079	***	0.924	0.013
Has Won Research Grants	0.235	***	1.265	0.024	0.350	***	1.419	0.013	0.341	***	1.407	0.017
Total Article Count	0.038	***	1.039	0.001	0.021	***	1.021	0.000	0.064	***	1.066	0.001
Log(θ)	1.369	***	3.932	0.042	0.209	***	1.232	0.015	0.581	***	1.788	0.024
Constant	1.141	***	3.131	0.051	1.222	***	3.393	0.026	0.391	***	1.478	0.029
	Zero Hurdle Component				Zero Hurdle Component				Zero Hurdle Component
Gender is Male	0.040		1.041	0.139	0.070		1.072	0.052	0.111	***	1.118	0.033
Institution is Public	0.140		1.150	0.224	−0.078		0.925	0.050	−0.139	***	0.870	0.036
Institution is AAU Member	−0.060		0.942	0.139	0.388	***	1.474	0.046	0.428	***	1.534	0.033
Years Since Degree	−0.009		0.991	0.007	−0.016	***	0.984	0.002	−0.009	***	0.991	0.002
Professorial Rank	−0.128		0.880	0.110	0.090	*	1.094	0.039	0.000		1.000	0.030
Has Won Research Grants	0.408	*	1.504	0.181	0.427	***	1.533	0.053	0.476	***	1.610	0.055
Total Article Count	0.442	***	1.555	0.021	0.519	***	1.680	0.009	0.342	***	1.408	0.005
Constant	−0.870	**	0.419	0.296	−1.105	***	0.331	0.087	−1.469	***	0.230	0.060
Observations	3,913				30,415				28,228
Log-likelihood	−9,894				−87,620				−51,720

	Nat. Res. & Conservation				Phys. & Math. Sci.				Soc. & Behav. Sci.
	β	Sig.	e^β	Std. Err.	β	Sig.	e^β	Std. Err.	β	Sig.	e^β	Std. Err.
	Positive Count Component				Positive Count Component				Positive Count Component
Gender is Male	0.011		1.011	0.026	0.042	**	1.043	0.015	0.016		1.017	0.015
Institution is Public	−0.071	*	0.932	0.033	−0.099	***	0.906	0.014	−0.060	***	0.942	0.016
Institution is AAU Member	0.106	***	1.112	0.024	0.287	***	1.332	0.013	0.219	***	1.245	0.015
Years Since Degree	−0.004	**	0.996	0.001	−0.005	***	0.995	0.001	0.003	**	1.003	0.001
Professorial Rank	0.023		1.024	0.021	0.098	***	1.103	0.011	−0.079	***	0.924	0.013
Has Won Research Grants	0.235	***	1.265	0.024	0.350	***	1.419	0.013	0.341	***	1.407	0.017
Total Article Count	0.038	***	1.039	0.001	0.021	***	1.021	0.000	0.064	***	1.066	0.001
Log(θ)	1.369	***	3.932	0.042	0.209	***	1.232	0.015	0.581	***	1.788	0.024
Constant	1.141	***	3.131	0.051	1.222	***	3.393	0.026	0.391	***	1.478	0.029
	Zero Hurdle Component				Zero Hurdle Component				Zero Hurdle Component
Gender is Male	0.040		1.041	0.139	0.070		1.072	0.052	0.111	***	1.118	0.033
Institution is Public	0.140		1.150	0.224	−0.078		0.925	0.050	−0.139	***	0.870	0.036
Institution is AAU Member	−0.060		0.942	0.139	0.388	***	1.474	0.046	0.428	***	1.534	0.033
Years Since Degree	−0.009		0.991	0.007	−0.016	***	0.984	0.002	−0.009	***	0.991	0.002
Professorial Rank	−0.128		0.880	0.110	0.090	*	1.094	0.039	0.000		1.000	0.030
Has Won Research Grants	0.408	*	1.504	0.181	0.427	***	1.533	0.053	0.476	***	1.610	0.055
Total Article Count	0.442	***	1.555	0.021	0.519	***	1.680	0.009	0.342	***	1.408	0.005
Constant	−0.870	**	0.419	0.296	−1.105	***	0.331	0.087	−1.469	***	0.230	0.060
Observations	3,913				30,415				28,228
Log-likelihood	−9,894				−87,620				−51,720

* p < 0.05; ** p < 0.01; *** p < 0.001.

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