a. Was this a controlled experiment or an observational study? Explain how you know
OA. This was an observational study. There was no random assignment to treatment/control groups. The subjects kept a food diary and had their blood drawn
OB. This was an observational study There was a random assignment to treatment/control groups. The subjects kept a food diary and had their blood drawn
OC. This was a controlled experiment. There was a random assignment to treatment/control groups. The subjects kept a food diary and had their blood drawn.
OD. This was a controlled experiment. There was no random assignment to treatment/control groups. The subjects kept a food diary and had their blood drawn.
b. Assuming the study was properly conducted, can we conclude that higher consumption of carbohydrates causes more severe acne? Explain.
We
make a cause-and-effect conclusion since

The study described, where individuals diagnosed with diabetes are compared to controls based on soda consumption, is an observational study. This identification is supported by the absence of random assignment to treatment/control groups, which is a characteristic of observational studies.

Causation vs. Correlation

Observational studies can only establish correlations and not causations. In this case, while the study may show a relationship between soda consumption and diabetes, it cannot definitively prove that higher soda consumption causes diabetes due to the nature of observational studies.

Learn more about types of scientific studies here:

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