Q: Which of the following equations best represents the concept of confounding in a study?

$$x \rightarrow y$$ \text{ and } z \rightarrow y$

Question 1

Which of the following best describes an observational study?

Accepted Answer

Researchers passively observe participants in their natural environment without assigning choices.

Question 2

A study finds that students who play musical instruments have higher GPAs than those who do not. Which of the following is a lurking variable that could explain this association?

Accepted Answer

Parental support and socioeconomic status.

Question 3

Why can’t observational studies establish causation?

Accepted Answer

They cannot control for all possible lurking variables that may influence the results.

Question 4

Which type of study is most appropriate for investigating the causes of a rare disease that occurred in the past?

Accepted Answer

Retrospective study

Question 5

In a prospective study, which of the following is true?

Accepted Answer

Subjects are identified in advance and data is collected as events unfold.

Question 6

A researcher asks 1,000 people if they use their phones before sleep and how much sleep they get. What type of study is this?

Accepted Answer

Cross-sectional study

Question 7

Which of the following is a disadvantage of retrospective studies?

Accepted Answer

They may rely on unreliable memories and incomplete historical records.

Question 8

Suppose you fertilize half your tomato plants and observe that they grow more tomatoes, but the non-fertilized plants were in the shade. What statistical issue does this illustrate?

Accepted Answer

Confounding

Question 9

In the context of insurance claims, a strong positive association is found between the number of firefighters at a fire and the amount of damage caused. What is the most likely explanation?

Accepted Answer

A lurking variable, such as the size of the fire, increases both the number of firefighters and the amount of damage.

Question 10

Which of the following equations best represents the concept of confounding in a study?

Accepted Answer

$$x ightarrow y$$ 	ext{ and } z ightarrow y$

Question 11

A cross-sectional study is most likely to be unreliable when:

Accepted Answer

The outcome for either the explanatory or response variable is rare in the general population.

Question 12

Which of the following is a key advantage of prospective studies?

Accepted Answer

Researchers can design the study to their specifications and isolate variables.

Question 13

Which of the following best describes a lurking variable?

Accepted Answer

A variable that influences both the explanatory and response variables but is not included in the study.

Question 14

Which of the following is a common use of retrospective studies in public health?

Accepted Answer

To study rare diseases by looking into patients' histories for possible causes.

Question 15

Which of the following statements is true about observational studies?

Accepted Answer

They are good for discovering associations but not for proving causation.

Question 16

A researcher wants to know if breast-fed babies live longer than bottle-fed babies. Which type of study would be most appropriate?

Accepted Answer

Prospective study

Question 17

Which of the following is a limitation of prospective studies?

Accepted Answer

They can be expensive and take a long time to complete.

Question 18

In a case-controlled study, which group is identified first?

Accepted Answer

People with the outcome (disease) of interest

Question 19

Which of the following best illustrates a common response due to a lurking variable?

Accepted Answer

Both the number of ice creams sold and the number of drowning incidents increase during summer due to higher temperatures.

Question 20

Which of the following is NOT a characteristic of an observational study?

Accepted Answer

Researchers manipulate the explanatory variable.

Observational Studies and Causality in Statistics

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