The highest-ranking detectives in the city’s police department are also the most adept at solving crimes. ███ ██ ████ ██ ███ ████ ███ ██████ ███ ███████ ███████ ████ ███ ███ ████████ ███████████████ ██████████ ██ ███████ ████████ █████ ███ ████ ██ ██████ ████ ███ ███████ ███████ ████ ███ ███ ██████████████ ███████████
The stimulus points out a surprising phenomenon: even though the highest-ranking detectives in the city's police department are the best at solving crimes, their rate of successfully solving cases in the last ten years has been no higher than the average success rate of the lowest-ranking detectives in the department.
The comparison between the success rates of the highest-ranking and lowest-ranking detectives is only surprising if we assume that they are facing cases of a similar level of difficulty. We can assume that if a high-ranking detective and a low-ranking detective were each given ten cases of the same level of difficulty, the high-ranking detective would have a higher rate of success than the low-ranking detective.
But it would make sense for the highest-ranking detectives to be assigned the most difficult cases — i.e., the hardest ones to solve. In that case, the fact that their success rate in solving such cases is no higher than the success rate of the lowest-ranking detectives for their (presumably less difficult) cases would say more about the difficulty of the cases than about the ability of the detectives. So learning about the relative difficulty of these cases would provide a straightforward way to resolve the tension in the stimulus.
Which one of the following, ██ █████ ████ █████ ██ ███████ ███ ████████ ████████
The detectives who ████ ███ ███████ ███████ ████ ██ ███████ ████████ █████ ███ █████ ███ ████ ██████ ██ ██████████ ███ ████████
Irrelevant. The length of time someone has worked as a detective doesn't help us explain why the success rate of the highest-ranking detectives in solving cases is no higher than that of the lowest-ranking detectives.
It generally takes ██ █████ ███ █████ ███ █ █████████ ██ ████ ████ ███ ██████ ██ ███ ███████ █████ ██ ███ ████████ █████████ ██████
Irrelevant. How long it takes for someone to rise through the ranks doesn't help explain the tension in the stimulus.
Those detectives in ███ ██████ ██████████ ███ ███ ███ ████ █████ ██ ███████ ████████ █████ ███ ████ █████ ████ ██████ ██ ██████ ██ ███ ██████ ███████████
Incorrect. We're not interested in the turnover or retention rates for these detectives. We want to know why the highest-ranking detectives, who are the best at solving crimes, have not had a higher success rate solving cases over the last ten years than the lowest-ranking detectives.
The police department █████████ █████ ███ ████████ █████ ████ ██ ███████ ██ ██ ███ ███████ ██ █████ ██ ███ ██████████████ ███████████
Correct. In the analysis, we discussed how we could resolve the tension in the stimulus if we knew that the highest-ranking detectives were given the most difficult cases. But it works just as well to be told that the lowest-ranking detectives are given the easiest cases. This suggests that the lowest-ranking detectives might have a relatively high rate of solving cases, which helps explain why even the highest-ranking detectives have a success rate no higher than the lowest-ranking ones.
None of the ██████████████ ██████████ ██ ███ ██████ ██████████ ███ ██████████ ██ ███████ ████████ █████ █████ ██ ███████ ███ ██████ ███████████
Irrelevant. If anything, this actually intensifies the tension in the stimulus. If the lowest-ranking detectives have absolutely no crime-solving experience, then it seems even more puzzling why they have a crime-solving success rate as high or higher than the highest-ranking detectives.