Recently , Keane et al .
reported the discovery of a fading radio transient following FRB 150418 , and interpreted it as the afterglow of the FRB .
Williams & Berger , on the other hand , suggested that the radio transient is analogous to a group of variable radio sources , so that it could be a coincident AGN flare in the observational beam of the FRB .
A new observation with VLA showed a re-brightening , which is consistent with the AGN picture .
Here , using the radio survey data of Ofek et al. , we statistically examine the chance coincidence probability to produce an event like the FRB 150418 transient .
We find that the probabilities to produce a variable radio transient with at least the same variability amplitude and signal-to-noise ratio as the FRB 150415 transient , without and with the VLA point , are P _ { 1 } \sim 6 \times 10 ^ { -4 } and P _ { 1 } \sim 2 \times 10 ^ { -3 } , respectively .
In addition , the chance probability to have a fading transient detected following a random time ( FRB time ) is less than P _ { 2 } \sim 10 ^ { -2.9 \pm 1.3 } .
Putting these together and assuming that the number of radio sources within one Parkes beam is 16 , the final chance coincidence of having an FRB 150418-like radio transient to be unrelated to the FRB is < 10 ^ { -4.9 \pm 1.3 } and < 10 ^ { -4.4 \pm 1.3 } , respectively , without and with the VLA point .
We conclude that the radio transient following FRB 150418 has a low probability being an unrelated AGN flare , and the possibility of being the afterglow of FRB 150418 is not ruled out .