Question 1

Which of the following best describes the purpose of peer review in scientific research?

Accepted Answer

Peer review is a process where experts in a field evaluate a research report before it is published. This lends credibility because it implies that other experts agree the study was carried out properly.

Question 2

A pollster claims that conducting polls only when the margin of error is zero will improve survey results. Which of the following best evaluates this claim?

Accepted Answer

The statement does not make sense. The margin of error is always a feature of the sample statistic.

Question 3

A researcher claims: 'My experiment proved beyond a doubt that vitamin C can reduce the severity of colds, because I controlled the experiment carefully for every possible confounding variable.' What is the best critique of this claim?

Accepted Answer

The statement does not make sense because it is not always easy to discover confounding variables.

Question 4

In a study of 1,200 college students, each was asked whether he or she was a good person. Which of the following is the most relevant guideline for critically evaluating this statistical study?

Accepted Answer

Guideline 1: This is most relevant. 'Good' is not well defined and is difficult to measure.

Question 5

A news article claims that 'chocolate is rich in flavonoids, which may reduce the risk of coronary heart disease.' The article received funding from a candy company. Which of the following is the most likely source of bias in this study?

Accepted Answer

The researchers may have been more inclined to provide favorable results because funding was provided by a party with a definite interest.

Question 6

An author sends out 100,000 questionnaires to women and receives 4,500 replies. She then draws conclusions about the general population of all women. What is the most significant source of bias in this study?

Accepted Answer

Returning the questionnaires was voluntary.

Question 7

Which of the following would be the best way to reduce the bias identified in the previous question?

Accepted Answer

The author could have interviewed a randomly selected sample of women.

Question 8

A CNN report on a survey of America's top restaurants states that 'only nine restaurants achieved a rare 29 out of a possible 30 rating and none of those restaurants are in the Big Apple.' Which of the following is a crucial piece of information missing from this summary?

Accepted Answer

How the respondents were selected.

Question 9

A USA Today headline reported that 'More companies try to bet on forecasting weather.' What is a critical piece of information missing from this statement?

Accepted Answer

No information is given in the headline about whether the organizations that are betting on weather forecasting are private businesses or governments.

Question 10

Which of the following is an example of a confounding variable in a medical study testing a new drug for blood pressure?

Accepted Answer

Participants' diet during the study period.

Question 11

A study reports that 'students who sleep at least 8 hours before an exam score higher than those who do not.' Which of the following is a possible confounding variable?

Accepted Answer

Students' prior academic performance.

Question 12

A survey about public opinion on climate change is conducted only among university students. What is the most significant limitation of this study?

Accepted Answer

The sample is not representative of the general population.

Question 13

Which of the following best describes a bias that can occur if a pharmaceutical company funds a study on its own drug?

Accepted Answer

The researchers may be more likely to interpret results in favor of the drug.

Question 14

A study claims that 'eating breakfast improves academic performance.' Which of the following would be the best way to test this claim while minimizing bias?

Accepted Answer

Randomly assign students to eat or skip breakfast and compare their academic performance.

Question 15

Which of the following is the correct formula for the margin of error for a proportion at a 95% confidence level?

Accepted Answer

$$ME = 1.96 	imes \sqrt{\frac{p(1-p)}{n}}$$

Question 16

A study finds a statistically significant difference between two groups. Which of the following is a critical question to ask before accepting the results?

Accepted Answer

Were the groups randomly assigned?

Question 17

Which of the following best describes a self-selection bias?

Accepted Answer

When individuals choose whether or not to participate in a study, leading to a non-representative sample.

Question 18

A study reports a correlation between ice cream sales and drowning incidents. What is the most likely explanation for this correlation?

Accepted Answer

A confounding variable, such as temperature, affects both ice cream sales and drowning incidents.

Question 19

Which of the following is NOT a critical step in evaluating a statistical study?

Accepted Answer

Ensuring the study supports the researcher's personal beliefs.

Critical Thinking and Bias in Statistical Studies: Key Concepts and Examples

Guida di studio - Domande di pratica

Study guide - Flashcard