Examine the following scenarios, and state whether each represents an experiment or an observational study.
A total of 50 female tobacco smokers and 50 female non-tobacco smokers are chosen. Lung capacity of the women is compared.
A total of 100 asthma sufferers are randomly assigned to receive either a new treatment or a control. Asthma relief is measured.
Solution
It would be unethical to assign a woman to smoke tobacco as part of an experiment. Therefore, scientists need to use observational studies, as this one is.
The subjects were randomized into the treatment and control groups, making this an experiment.