Question 183·200 Super-Hard SAT Reading Questions·Information and Ideas
In a city-run pilot, researchers tested a smartphone app that offered real-time crowding predictions and small fare rebates for choosing less congested buses. In phase 1, riders opted in and used the app; they reported 14% shorter average commute times relative to nonusers on the same corridors. In phase 2, the researchers randomly assigned invitations across all routes, and the average time savings shrank to 4%, with the largest gains among riders who, in pre-study diaries, had indicated frequent willingness to depart earlier or later and who listed two or more viable bus lines for their origin–destination pair. Moreover, when the team restricted the phase-2 sample to corridors with only one bus line and fixed headways, the time savings disappeared. The authors note that the rebate amount and prediction accuracy were unchanged between phases, suggesting that ______
Which choice most logically completes the text?
For SAT Reading & Writing 'suggesting that' completion questions, first underline the key data points and patterns (here: 14% vs. 4%, who benefits most, what happens under special conditions, and what stays the same). Ask what overall explanation would tie these observations together, and mentally summarize that idea before looking at the choices. Then eliminate any options that introduce new, unsupported claims or contradict the given evidence, and choose the one that most directly paraphrases the logical inference you already formed.
Hints
Compare the two phases carefully
Ask yourself: what is different between phase 1 and phase 2 (in terms of who uses the app and how they are selected), and what is explicitly stated to be the same?
Look at which riders saved the most time in phase 2
In phase 2, which riders saw the largest gains? What did their pre-study diaries say about their willingness to change departure times and the number of bus lines available to them?
Use the single-line, fixed-headway corridors clue
On corridors with only one bus line and fixed headways, the time savings disappeared. What does that tell you about what is necessary for the app to reduce commute times?
Eliminate answers that add new, unsupported ideas
Check each choice for claims that the passage never mentions (like changing the rebate size, measurement errors, or extra 'noise'). The best answer will restate and connect the patterns already described in the passage.
Step-by-step Explanation
Understand what changed between phase 1 and phase 2
In phase 1, riders opted in to use the app and reported 14% shorter commute times than nonusers on the same corridors. In phase 2, invitations were randomly assigned and the average time savings dropped to 4%. The authors also say that the rebate amount and prediction accuracy were unchanged between phases, so those parts of the app were not different.
So the main change was who used the app (self-selected in phase 1 vs. randomly selected in phase 2), not what the app did.
Focus on who benefited most in phase 2
The passage specifies that in phase 2, the largest gains were among riders who:
- had often said in pre-study diaries that they were willing to depart earlier or later, and
- listed two or more viable bus lines for their origin–destination pair.
These people had more flexibility (they could change departure times and bus lines). That tells you the app is especially helpful for riders who can actually act on its crowding predictions by adjusting when or which bus they take.
Use the single-line corridor result to sharpen the inference
The passage then says that when researchers looked only at corridors with one bus line and fixed headways (fixed schedule), the time savings disappeared. On such routes, riders have almost no flexibility: they can’t switch lines and can’t really change when the bus comes.
If time savings vanish when there’s no flexibility, that is strong evidence that the savings depend on being able to change routes or departure times, not on the rebate amount or prediction accuracy themselves (since those were constant).
Match the inference to the answer choices
The blank follows the phrase 'suggesting that', so the correct completion must explain why phase 1 showed large savings while phase 2 showed much smaller savings, and why the benefits were concentrated among flexible riders and absent on inflexible corridors.
Choice A says that the big phase-1 savings mostly came from opt-in riders having more ability to shift departure times or switch routes, rather than from any improvement in rebates or predictions. This directly matches the evidence about flexible riders and the unchanged app features, so A is the correct answer.