Crowd featureBefore obstacleAfter obstacleOverallDensity0.85920.73080.7447Velocity−0.9357−0.9518−0.8587Researcher Xiaolu Jia and colleagues monitored ...
GMAT Information and Ideas : (Ideas) Questions
| Crowd feature | Before obstacle | After obstacle | Overall |
|---|---|---|---|
| Density | 0.8592 | 0.7308 | 0.7447 |
| Velocity | −0.9357 | −0.9518 | −0.8587 |
Researcher Xiaolu Jia and colleagues monitored individuals' velocity and the surrounding crowd density as a group of study participants walked through a space and navigated around an obstacle. Participants rated how congested it seemed before the obstacle, after the obstacle, and overall, and the researchers correlated those ratings with velocity and density. (Correlations range from \(-1\) to \(1\), with greater distance from \(0\) indicating greater strength). The researchers concluded that the correlations with velocity are stronger than those with density.
Which choice best describes data from the table that support the researchers' conclusion?
The correlation between congestion ratings before the obstacle and density is further from 0 than the correlation between overall congestion rating and velocity is.
The correlation between congestion ratings before the obstacle and velocity is further from 0 than the correlation between congestion overall and velocity is.
For each of the three ratings, the correlation with velocity is negative while the correlation with density is positive.
For each of the three ratings, correlations with velocity are further from 0 than the corresponding correlations with density are.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Researcher Xiaolu Jia and colleagues monitored individuals' velocity and the surrounding crowd density as a group of study participants walked through a space and navigated around an obstacle." |
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| "Participants rated how congested it seemed before the obstacle, after the obstacle, and overall, and the researchers correlated those ratings with velocity and density." |
|
| "(Correlations range from −1 to 1, with greater distance from 0 indicating greater strength)." |
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| "The researchers concluded that the correlations with velocity are stronger than those with density." |
|
Part B: Provide Passage Architecture & Core Elements
Main Point: Researchers found that people's congestion ratings correlate more strongly with walking velocity than with crowd density when navigating around obstacles.
Argument Flow: The passage first establishes the experimental setup where researchers tracked both movement metrics and subjective ratings. It then explains how to interpret correlation strength before presenting the key finding that velocity shows stronger correlations with perceived congestion than density does.
Step 2: Interpret the Question Precisely
What's being asked? We need to identify which data from the table supports the researchers' conclusion that velocity correlations are stronger than density correlations.
What type of answer do we need? Evidence from the numerical data that demonstrates velocity correlations are consistently further from \(0\) than density correlations.
Any limiting keywords? "support the researchers' conclusion" - we must find data that backs up their specific claim about correlation strength.
Step 3: Prethink the Answer
- The researchers concluded that velocity correlations are stronger than density correlations
- Since correlation strength is measured by distance from \(0\), we need evidence showing that velocity correlations are consistently further from \(0\) than density correlations across all three rating conditions
The correlation between congestion ratings before the obstacle and density is further from 0 than the correlation between overall congestion rating and velocity is.
✗ Incorrect
- Compares density before obstacle (\(\mathrm{0.8592}\)) with velocity overall (\(\mathrm{0.8587}\))
- Actually shows density correlation is slightly further from \(\mathrm{0}\)
- This comparison doesn't support the researchers' conclusion
The correlation between congestion ratings before the obstacle and velocity is further from 0 than the correlation between congestion overall and velocity is.
✗ Incorrect
- Compares velocity before obstacle with velocity overall
- Both values are velocity correlations, so this doesn't compare velocity versus density strength
For each of the three ratings, the correlation with velocity is negative while the correlation with density is positive.
✗ Incorrect
- Correctly notes that velocity correlations are negative while density correlations are positive
- However, the researchers' conclusion is about correlation strength (distance from \(\mathrm{0}\)), not about positive versus negative signs
For each of the three ratings, correlations with velocity are further from 0 than the corresponding correlations with density are.
✓ Correct
- States that for each rating condition, velocity correlations are further from \(\mathrm{0}\) than density correlations
- Verification: Before (\(\mathrm{|-0.9357| > |0.8592|}\)), After (\(\mathrm{|-0.9518| > |0.7308|}\)), Overall (\(\mathrm{|-0.8587| > |0.7447|}\))
- This directly supports the researchers' conclusion about correlation strength across all three conditions