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. (4 points)

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

Step-by-step explanation:

A study that record the characteristics of a population by studying individuals in a sample, but does not manipulate variables of interest is known as an operational study. Like in the first study only effects have been noted.

A controlled experiment is an experiment where the variable of interest is directly manipulated by a scientist, in order to test a single variable at a time.

Like in the second study, the subjects were under the control of the experimenter, to test the effect of oil.

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

d

step-by-step explanation:

d

d

step-by-step explanation: