When people predict that certain result will not take place unless a certain action is taken, they believe that they
have learned that the prediction is correct when the action is taken and the result occurs. On reflection,
however, it often becomes clear that the result admits of more than one interpretation.
Which of the following, if true, best supports the claims above?
Fire ants have invaded much of the southern United States and, as a result, horned lizards have disappeared in
invaded areas, because the fire ants, which sting aggressively, kill the young lizards and eliminate the harvester
ants that are the lizards’ primary food. Populations of horned lizards have declined even in those southern
localities that as yet remain free of fire ants, but ecologists believe that decline is also attributable to the
southern states’ invasion by fire ants?
Which of the following, if true, provides the strongest justification for the ecologists’ belief?
Correctly measuring the productivity of service workers is complex. Consider, for example, postal workers: they
are often said to be more productive if more letters are delivered per postal worker. But is this really true? What
if more letters are lost or delayed per worker at the same time that more are delivered?
The objection implied above to the productivity measure described is based on doubts about the truth of which
of the following statements?