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eatheng4441
eatheng4441
06.11.2020 • 
Mathematics

In one study on the effect of argan oil on wrinkles, 125 subjects who acknowledged being long-time argan oil users had their wrinkles compared with those of 125 people who had never used argan oil. In a second study, 75 subjects were chosen randomly to use argan oil and 75 were chosen to use a placebo. Identify the types of studies performed. The first study was a controlled experiment whereas the second was an observational study.

The first study was an observational study whereas the second was a controlled experiment.

Both studies were controlled experiments.

Both studies were observational studies.

Each study was part controlled experiment and part observational study.

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