Question 56·Medium·Inferences
Over the summer, a mid-sized city installed highly visible pedestrian crosswalk markings at 60 intersections. Officials later pointed to a citywide 18% drop in pedestrian-involved collisions over the next six months as evidence that the markings improved safety. During that same period, however, the city also lowered the default speed limit from 30 to 25 miles per hour and added speed cameras on major corridors where many of the new markings were placed. A research team noted that intersections without new markings but located on corridors with cameras showed declines similar to those with new markings. Therefore, the team concludes that ______
Which choice most logically completes the text?
For logical-completion inference questions, identify the claim being challenged, then restate what the new evidence shows. Choose the option that matches what the evidence justifies (often a limited conclusion like “cannot be attributed solely to X”), and avoid choices that make stronger causal claims than the passage supports.
Hints
Separate the officials’ claim from the research team’s conclusion
What are officials trying to prove, and what new evidence is the research team using to challenge that interpretation?
Look for other changes happening at the same time
List the other changes that happened during the same six months besides adding crosswalk markings.
Compare intersections with and without markings
If intersections without new markings still saw similar declines when cameras were present, what does that imply about blaming the markings alone?
Step-by-step Explanation
Identify what the officials claimed
The city officials point to an 18% citywide drop in pedestrian-involved collisions and treat it as evidence that the new crosswalk markings improved safety.
Account for other changes happening at the same time
During the same period, the city also lowered the speed limit and added speed cameras on major corridors, meaning there are multiple plausible contributors to the decline.
Use the research team’s comparison
The team notes that intersections without new markings but on corridors with cameras showed collision declines similar to intersections with new markings. That undermines the claim that markings alone explain the change.
Choose the conclusion that matches this reasoning
Since similar declines occurred even where the markings were not installed (as long as cameras were present), the markings cannot be credited as the only cause of the decline. Therefore, the best completion is: “the crosswalk markings cannot be credited as the sole cause of the decline in pedestrian collisions.”