Question 152·Medium·Command of Evidence
Urban ecologists examined whether installing green roofs—layers of soil and vegetation placed atop conventional roofs—can reduce summertime indoor temperatures in apartment buildings. Over one July–August period, the researchers collected hourly temperature data from twenty apartment buildings of similar height and construction: ten with newly installed green roofs and ten without. They concluded that green roofs are a primary factor in lowering indoor temperatures during hot weather.
Which finding, if true, would most directly support the researchers’ conclusion?
For “support the conclusion” questions, first underline the exact claim (here, that green roofs are a primary cause of lower indoor temperatures). Then, look for answer choices that give direct, comparative evidence: data or observations that clearly contrast the group with the key feature (green roofs) and the group without it, ideally while keeping other conditions constant. Quickly cross out choices that give only background information, side effects (like satisfaction or costs) without group differences, or facts that could be true regardless of whether the claim is correct. Focus your time on the one option that most clearly shows the predicted effect in the group that has the factor being tested.
Hints
Focus on the conclusion you are supporting
The researchers are claiming that green roofs cause lower indoor temperatures. Ask yourself: what kind of result would best show that this is true?
Look for a direct comparison
Among the choices, which ones actually compare buildings with green roofs to buildings without them, rather than just describing one group or giving general background?
Think about controlling other factors
Which option makes it clear that other conditions (like the buildings’ basic construction or the weather outside) are not the main reason for any difference between the two groups?
Step-by-step Explanation
Restate what the researchers are claiming
The conclusion says green roofs are a primary factor in lowering indoor temperatures during hot weather. In other words, the presence of a green roof is causing cooler indoor temperatures compared with buildings that don’t have one.
Decide what kind of evidence would be strongest
To most directly support a causal claim like this, you want evidence that:
- Compares buildings with green roofs to buildings without them.
- Shows a consistent difference in indoor temperature between the two groups.
- Keeps other conditions (like outdoor temperature and basic building characteristics) the same, so the green roof is the main thing that’s different.
Eliminate choices that don’t mention indoor temperature differences
Check each option and ask: Does this tell me anything about how indoor temperatures compare between buildings with and without green roofs?
- One choice talks about residents’ satisfaction with appearance only (no temperatures at all).
- Another describes similarities in construction (age, insulation, windows) but does not state any temperature results.
- Another mentions energy-use costs rising for all twenty buildings, again with no comparison between the green-roof and non–green-roof groups. None of these directly shows that green roofs made buildings cooler inside.
Select the option that directly links green roofs to cooler indoor temperatures
The remaining option says that throughout the study, buildings with green roofs had average daytime indoor temperatures 3 °C lower than comparable buildings without green roofs, while outdoor temperatures near all buildings were the same. This directly compares the two groups and controls for outdoor conditions, making the green roofs the key difference that explains the lower indoor temperatures. Therefore, the correct answer is: “Throughout the study period, the average daytime indoor temperature in buildings with green roofs was 3 °C lower than in comparable buildings without green roofs, while outdoor temperatures near all buildings were the same.”