In a study conducted over several years, seabird and domesticated cat populations on a geographically isolated island changed from year...

GMAT Two Part Analysis : (TPA) Questions

Source: Official Guide

Two Part Analysis

Verbal - RC

HARD

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In a study conducted over several years, seabird and domesticated cat populations on a geographically isolated island changed from year to year. Researchers found that over the course of the study, the relationship (R) between seabirds and domesticated cats was such that the island's seabird population was three times as likely to decrease from the previous year if the island's domesticated cat population increased (even if slightly) during the same year. The researchers are about to begin a second, follow-up study with the same duration as the first study. Based on recent trends, the researchers made the following projections: R will hold and the island's domesticated cat population will decrease during more years of the second study than it did in their first study.

Assuming that the information above is true, select for Can be inferred as true the statement that can be most reasonably inferred as true from the information provided, and select for Can be inferred as false the statement that can be most reasonably inferred as false from the information provided. Make only two selections, one in each column.

Can be inferred as true

Can be inferred as false

If the researchers' projections are accurate, the island's seabird population is likely to increase during more years of the second study than it did in the first.

During the first study, most years had an increase in the island's domesticated cat population.

If the researchers' projections are accurate, the island's seabird population is likely to increase during most of the years of the second study.

During the first study, the island's seabird population decreased only when the island's domesticated cat population increased.

During the first study, most years during which the island's seabird population decreased were years during which the island's domesticated cat population increased.

Solution

Phase 1: Owning the Dataset

Argument Analysis Table

Passage Statement	Analysis & Implications
"Relationship (R): seabird population was three times as likely to decrease from previous year if cat population increased"	Core Fact: Establishes conditional probability, not absolute causation Visualization: If seabirds decrease 10% of the time normally, they decrease 30% when cats increase Logical Connections: Correlation, not exclusive causation What We Can Conclude: Seabirds can decrease even without cat increases
"Projections: R will hold and cat population will decrease during more years of second study than first study"	Core Fact: More years of cat decreases in second study Visualization: If first study had 2 years of cat decreases, second might have 4+ Logical Connections: Combines with R to affect seabird likelihood What We Can Conclude: Fewer opportunities for cat-increase-triggered seabird decreases

Key Patterns Identified

Established Facts: Probabilistic relationship (3x), comparative trend (more decreases)
Relationships: Inverse correlation between cat increases and seabird stability
Valid Conclusions: Can combine R with projection about cat decreases
Limitations: Cannot assume absolutes from probabilities

Phase 2: Question Analysis & Prethinking

Understanding Each Part

Part 1 (True): Need a statement that logically follows from given facts
Part 2 (False): Need a statement that contradicts the given facts
Relationship: Both should independently demonstrate understanding of the probabilistic relationship

Valid Inferences Generated

If cats decrease more, seabirds less likely to decrease (follows from R + projection)
Seabirds could decrease without cat increases (R shows probability, not exclusivity)
Cannot determine absolute frequencies (only relative comparisons given)

Phase 3: Answer Choice Evaluation

Choice Analysis

Choice 1: "If projections accurate, seabird population likely to increase during more years of second study than first"

Claim: More years of seabird increases in second study
Support: Cats decrease more → fewer cat increases → fewer triggers for seabird decreases
Validity: Strong logical inference from combining facts
Suitability: Good for TRUE

Choice 2: "During first study, most years had increase in cat population"

Claim: Majority of years had cat increases
Support: We only know relative comparison, not absolute frequencies
Validity: Cannot be determined from given information
Suitability: Neither true nor false

Choice 3: "If projections accurate, seabird population likely to increase during most years of second study"

Claim: Absolute majority claim
Support: Too strong; we only know relative improvement
Validity: Over-inference
Suitability: Neither definitively true nor false

Choice 4: "During first study, seabird population decreased only when cat population increased"

Claim: Exclusive causation
Support: R states "3x as likely," not "only when"
Validity: Contradicts the probabilistic nature of R
Suitability: Perfect for FALSE

Choice 5: "During first study, most years when seabirds decreased were years when cats increased"

Claim: Correlation claim about frequency
Support: 3x likelihood suggests this, but not definitively
Validity: Plausible but not necessarily true
Suitability: Neither definitively true nor false

Final Selection

Can be inferred as TRUE: Choice 1 - Logical consequence of cats decreasing more + relationship R
Can be inferred as FALSE: Choice 4 - Contradicts probabilistic nature of relationship R

The key insight is recognizing that "3x as likely" means probability, not exclusivity. Seabirds can still decrease without cat increases, just less frequently.

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