An Empirical Study on Response to Online Customer Reviews and E-Commerce Sales: From the Mobile Information System Perspective

Table 6

Results of robustness test (subsample from July 2018 to November 2018).

	SYS-GMM model		Fixed effect of panel data
	Model 1	Model 2	Model 3	Model 4
Ratio of response to negative review	0.509 (0.115)	0.596 (0.097)	0.396 (0.088)	0.259 (0.086)
Ratio of response to positive review	0.128 (0.030)	0.094 (0.011)	0.109 (0.034)	0.083 (0.011)
Wald test value ( value)	3.93 (0.000)	3.51 (0.000)	2.98 (0.000)	3.27 (0.000)
Ratio of response to negative review × product price		0.069 (0.018)		0.055 (0.019)
Ratio of response to positive review × product price		0.277 (0.089)		0.210 (0.036)
Ratio of response to negative review × product heterogeneity		0.089 (0.014)		0.149 (0.048)
Ratio of response to positive review × product heterogeneity		0.137 (0.055)		0.153 (0.022)
Other control variable	Included	Included	Included	Included
Wald chi^2	996.73	2,115.69
Sargan test ( value)	15.771 (1.101)	19.932 (1.175)
AR^2 ( value)	0.939 (0.195)	1.101 (0.139)
R^2			0.202	0.227
F value			89.93	110.72
Number of observed values	13951	13951	13951	13951

Note. The dependent variable is the sales volume. “” and “” in the table mean that z-statistics are significant at the levels of 5% and 1%.