Exploring the effects of journal article features: Implications for automated prediction of scholarly impact

Estimates of linear models for the log impact of articles with fixed effects for the journals overall_

		Coef.	Std Err.	t	P>t	[95% Conf. Interval]
X1	(log) n. authors	0.085	0.001	66.1	<0.01	0.082	0.087
X2	(log) n. countries	0.041	0.002	24.4	<0.01	0.037	0.044
X3	(log) avg authors quality	0.224	0.001	242.3	<0.01	0.222	0.226
X4	Women	-0.024	0.001	-17.1	<0.01	-0.026	-0.021
X5	English	-0.022	0.002	-15.0	<0.01	-0.025	-0.020
X6	open access	0.070	0.002	38.5	<0.01	0.066	0.073
X7	(log) n. pages	0.200	0.002	86.8	<0.01	0.195	0.204
X8	(log) n. references	0.268	0.002	165.8	<0.01	0.265	0.271
X9	% references in WoS	0.002	0.000	39.2	<0.01	0.002	0.002
X10	(log) cited articles age	-0.374	0.002	-231.6	<0.01	-0.377	-0.370
X11	(log) cited articles impact	0.061	0.001	97.5	<0.01	0.060	0.063
	Intercept	-1.436	0.007	-201.9	<0.01	-1.450	-1.422

Number of articles per area of the journal_

	Area	N. of articles
1	Arts and Humanities	17,816
2	Biology	251,921
3	Biomedical Research	164,805
4	Chemistry	194,405
5	Clinical Medicine	316,828
6	Earth and Space Sciences	116,736
7	Economics	40,308
8	Engineering	349,058
9	Law, political and social sciences	65,344
10	Mathematics	57,718
11	Multidisciplinary Sciences	66,985
12	Physics	227,595
13	Psychology	30,896
	Total	1,900,415

Summary statistics of the variables of the dataset (1,427,670 articles)_

	Variable	Mean	Std dev.	Min	Max
Y	impact	0.871	1.992	0	1,039.638
X1	n. authors	5.476	3.959	1	100
X2	n. countries	1.417	0.894	1	44
X3	avg authors quality	1.015	1.053	0.001	204.831
X4	Women	0.605	0.489	0	1
X5	English	0.395	0.489	0	1
X6	open access	0.453	0.498	0	1
X7	n. pages	11.000	6.259	1	100
X8	n. references	41.317	22.570	1	200
X9	% references in WoS	76.874	20.630	0.515	100
X10	cited articles age	9.431	3.716	0	37
X11	cited articles impact	11.800	23.462	0.010	1,995.620

Estimates of linear models for the log impact of the articles with fixed effects for the journals (standard errors in parenthesis)‡, by area_

Area‡	1	2	3	4	5	6	7	8	9	10	11	12	13
X1 (log) n. authors	0.079	0.082	0.072	0.044	0.088	0.105	0.122	0.071	0.069	0.087	0.111	0.084	0.057
	(0.018)	(0.003)	(0.004)	(0.003)	(0.003)	(0.004)	(0.009)	(0.003)	(0.007)	(0.009)	(0.005)	(0.003)	(0.009)
X2 (log) n. countries	0.109	0.033	0.044	0.009†	0.045	0.055	0.075	0.039	0.056	0.112	-0.002†	0.034	0.053
	(0.026)	(0.004)	(0.005)	(0.005)	(0.003)	(0.005)	(0.010)	(0.004)	(0.010)	(0.010)	(0.007)	(0.004)	(0.012)
X3 (log) avg authors quality	0.179	0.235	0.177	0.282	0.157	0.225	0.220	0.242	0.212	0.299	0.233	0.259	0.243
	(0.008)	(0.002)	(0.003)	(0.003)	(0.002)	(0.003)	(0.005)	(0.002)	(0.004)	(0.005)	(0.004)	(0.002)	(0.007)
X4 Women	0.024†	-0.034	-0.016	-0.023	-0.017	-0.053	-0.013†	-0.028	0.011†	-0.044	-0.007†	-0.023	-0.011†
	(0.017)	(0.003)	(0.004)	(0.003)	(0.003)	(0.004)	(0.008)	(0.003)	(0.008)	(0.008)	(0.006)	(0.003)	(0.011)
X5 English	0.020†	-0.023	-0.019	-0.044	-0.005†	-0.054	-0.038	-0.033	0.017†	-0.052	-0.002†	-0.014	-0.008†
	(0.017)	(0.003)	(0.004)	(0.004)	(0.003)	(0.005)	(0.009)	(0.003)	(0.008)	(0.008)	(0.006)	(0.004)	(0.010)
X6 open access	0.164	0.070	0.101	0.020	0.114	0.068	0.087	0.037	0.139	0.038	0.087	0.033	0.079
	(0.018)	(0.004)	(0.006)	(0.004)	(0.004)	(0.006)	(0.009)	(0.004)	(0.008)	(0.010)	(0.018)	(0.004)	(0.010)
X7 (log) n. pages	0.230	0.169	0.230	0.217	0.270	0.205	0.134	0.193	0.218	0.090	0.086	0.221	0.187
	(0.026)	(0.005)	(0.007)	(0.006)	(0.005)	(0.008)	(0.015)	(0.005)	(0.013)	(0.010)	(0.011)	(0.005)	(0.018)
X8 (log) n. references	0.269	0.277	0.239	0.249	0.243	0.267	0.313	0.268	0.275	0.316	0.287	0.262	0.291
	(0.017)	(0.004)	(0.005)	(0.004)	(0.003)	(0.006)	(0.010)	(0.003)	(0.008)	(0.008)	(0.008)	(0.004)	(0.012)
X9 % references in WoS	0.007	0.002	0.001	0.000†	0.002	0.002	0.002	0.002	0.004	0.002	-0.000†	0.000	0.001
	(0.001)	(0.000)	(0.000)	(0.000)	(0.000)	(0.000)	(0.000)	(0.000)	(0.000)	(0.000)	(0.000)	(0.000)	(0.000)
X10 (log) cited articles age	-0.193	-0.408	-0.383	-0.456	-0.319	-0.414	-0.490	-0.386	-0.322	-0.357	-0.429	-0.395	-0.463
	(0.013)	(0.004)	(0.005)	(0.004)	(0.004)	(0.006)	(0.011)	(0.003)	(0.008)	(0.009)	(0.008)	(0.004)	(0.015)
X11 (log) cited articles impact	0.093	0.043	0.070	0.029	0.075	0.090	0.127	0.076	0.096	0.103	0.051	0.045	0.093
	(0.008)	(0.001)	(0.002)	(0.001)	(0.001)	(0.003)	(0.005)	(0.001)	(0.004)	(0.004)	(0.003)	(0.002)	(0.005)
Intercept	-2.312	-1.264	-1.377	-0.952	-1.676	-1.409	-1.308	-1.326	-1.821	-1.303	-1.160	-1.269	-1.266
	(0.071)	(0.017)	(0.021)	(0.021)	(0.015)	(0.025)	(0.047)	(0.015)	(0.036)	(0.037)	(0.038)	(0.018)	(0.056)
Number of articles	17,816	251,921	164,805	194,405	316,828	116,736	40,308	349,058	65,344	57,718	66,985	227,595	30,896
Number of journals	1,618	2,187	1,187	600	2,954	931	919	2,104	1,800	746	202	864	525
R-squared	0.26	0.27	0.26	0.31	0.24	0.27	0.28	0.28	0.22	0.26	0.24	0.30	0.22
Intra-journal correlation	0.32	0.27	0.29	0.34	0.28	0.24	0.26	0.28	0.25	0.18	0.39	0.26	0.26