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Question

Researchers want to study how coffee drinking affects lung cancer.  They randomly selected a group of 5,000 people and assigned them by randomization into either a group that drinks coffee or a group that does not drink coffee during the study period. The participants are studied for a period of 10 years. Show work

a.         What is the exposure?

b.         What is the outcome?

c.         Is this study an observational study or an experimental study?  Explain.

Answer 1

a. What is the exposure?

The exposure in this study is "drinking coffee." Researchers are interested in seeing how being exposed to this specific behavior (i.e., consuming coffee) affects lung cancer rates among the participants. Those in the group assigned to drink coffee are considered exposed, while those in the group not drinking coffee during the study period are considered unexposed.

b. What is the outcome?

The outcome in this study is the development of "lung cancer." Researchers will be comparing the rates or incidences of lung cancer between the group that drinks coffee and the group that does not, over the 10-year study period. The outcome is what the study is ultimately trying to measure or observe as being potentially affected by the exposure.

c. Is this study an observational study or an experimental study? Explain.

This study is an experimental study, specifically a randomized controlled trial (RCT). In an experimental study, the researcher actively intervenes and assigns participants into groups with different exposures to see how these exposures affect outcomes. The key here is the random assignment of participants to either the coffee-drinking group or the non-coffee drinking group. This randomization is a hallmark of experimental designs and helps to control for confounding variables, ensuring that the observed effects on lung cancer can be more confidently attributed to the coffee consumption itself and not to other factors. Observational studies, in contrast, involve no such intervention by the researcher; instead, they observe and record events or characteristics without altering them. Since this study involves actively dictating whether participants drink coffee or not and then observing the outcome (lung cancer) over time, it is experimental.

Answer 2

1. What is the exposure? The exposure in this study is coffee drinking. The investigators are interested in studying the effects of coffee consumption on lung cancer.
2. What is the outcome? The outcome is the occurrence of lung cancer. The investigators want to determine whether there is a correlation between drinking coffee and the development of cancer.
3. Is this study an observational study or an experimental study?  This study is an experimental study. The investigators randomly assigned the participants into two groups: one that drinks coffee and one that does not drink coffee. By randomly assignment the participants of the study, the researchers have control over the exposure (drinking coffee) and can compare the outcomes (occurrence of lung cancer) between the two groups. THis allows the investigators to determine whether there is a potential causal relationship between coffee drinking an cancer.