  It is under debate whether the magnetic field in the solar atmosphere carries
neutralized electric currents; particularly, whether a magnetic flux rope
(MFR), which is considered the core structure of coronal mass ejections,
carries neutralized electric currents. Recently Wang et al. (2023, ApJ, 943,
80) studied magnetic flux and electric current measured at the footpoints of 28
eruptive MFRs from 2010 to 2015. Because of the small sample size, no rigorous
statistics has been done. Here, we include 9 more events from 2016 to 2023 and
perform a series of nonparametric statistical tests at a significance level of
5\%. The tests confirm that there exist no significant differences in magnetic
properties between conjugated footpoints of the same MFR, which justifies the
method of identifying the MFR footpoints through coronal dimming. The tests
demonstrate that there exist no significant differences between MFRs with
pre-eruption dimming and those with only post-eruption dimming. However, there
is a medium level of association between MFRs carrying substantial net current
and those produce pre-eruption dimming, which can be understood by the
Lorentz-self force of the current channel. The tests also suggest that in
estimating the magnetic twist of MFRs, it is necessary to take into account the
spatially inhomogeneous distribution of electric current density and magnetic
field.
