Question

A researcher wants to know whether one of two different antihistamines work better to relieve hay fever. Consider the following observational study and experiment.

Experiment
She randomly selects 50 people with hay fever who do not take any medicine for it and randomly assigns them to take Drug A or Drug B. Before the study starts, she asks each person to list their symptoms. After 2 weeks of taking the medicine, she again asks each person to list their symptoms and records the difference.

Observational study
She randomly selects 25 people who have used Drug A for at least 2 weeks and 25 people who have used Drug B for at least 2 weeks. She asks them to list the differences of their symptoms before they started the drug treatment and after at least 2 weeks on the drug.

Which of the two, the given experiment or the given observational study, will give better information about which drug works better to reduce hay fever symptoms? Please explain your answer.

Answer 1

In this case the given experiment will give the better results.

Experiment
She randomly selects 50 people with hay fever who do not take any medicine for it and randomly assigns them to take Drug A or Drug B. Before the study starts, she asks each person to list their symptoms. After 2 weeks of taking the medicine, she again asks each person to list their symptoms and records the difference.

Here, the patients are identified and the symptoms are recorded initially and later will be recorded. In this scenario, the person will be able to observe the symptoms properly