A recent report shows that the number of collisions between vehicles at junctions with electronic advertising signs, and the number of such collisions at junctions that do not have such signs, are the same. The installation of electronic advertising signs at junctions, therefore, does not affect road safety.
Which of the following would it be most useful to establish in order to evaluate the argument?
Incorrect.
[[snippet]]The question in this answer choice is beside the point. Our task has nothing to do with solving the problem of road accidents. All we need to do is find a way of testing the author's conclusion.
Incorrect.
[[snippet]]This factor is irrelevant. The signs are already installed; considering how the government is dealing, or intends to deal, with the companies that install them will not help us find out whether the signs affect road safety.
Incorrect.
[[snippet]]This answer choice asks an unnecessary question. Road accidents are a problem even if only a few of them are fatal.
Incorrect.
[[snippet]]The efficiency of the signs has nothing to do with the author's conclusion and, therefore, cannot help us decide whether it's valid.
Great!
[[snippet]]The argument refers to collisions between vehicles but not to accidents involving pedestrians. If the number of accidents involving pedestrians is the same for both types of junction, then the signs probably don't have any effect on road safety. If the pedestrian accidents numbers for the junctions with signs are much higher, then they do affect road safety, and the author is wrong.