Inference Flashcards

A researcher notices that regions with higher literacy rates also have lower infant mortality. The most cautious inference is:

Answer: Literacy and infant mortality are inversely correlated.

Observational data establish a relationship between the two variables but cannot on their own prove causation or direction.

A coin is flipped ten times and lands heads each time. What is the best inference about the eleventh flip?

Answer: The probability of heads on the next flip remains approximately 50% for a fair coin.

For a fair coin, each flip is independent, so past results do not change the probability of future outcomes.

A news article states that a new drug reduced symptoms in 70% of trial participants. What is the most warranted inference?

Answer: The drug was effective for a majority of participants in the trial.

The stated statistic only justifies concluding that most trial participants experienced symptom reduction.

Tom says, 'Every time I wash my car, it rains.' From this statement alone, what can be inferred?

Answer: Tom has observed a coincidental pattern that he has not causally explained.

Tom is describing a perceived pattern, but the statement provides no causal mechanism linking car washing to precipitation.

An advertisement claims 'four out of five dentists recommend SparkleBright toothpaste.' Which inference is best supported?

Answer: In the survey cited, 80% of dentists recommended SparkleBright.

The claim only justifies inferring that 80% of dentists in the cited survey gave that recommendation; no broader conclusion is warranted.

Premises: 'If it snows, school is canceled. It did not snow.' What can be inferred?

Answer: Nothing can be determined about whether school was canceled.

The absence of snow only tells us the sufficient condition for cancellation was not met; school could still be canceled for other reasons.

A student scores in the 90th percentile on a standardized test. What does this most accurately indicate?

Answer: The student scored higher than 90% of test takers.

A percentile rank indicates relative standing among test takers, not a percentage of questions answered correctly.