A placebo is a medically ineffectual treatment that looks like a real treatment. Sometimes patients given a placebo treatment, unaware of the fact that it is indeed a placebo, will have a perceived or actual improvement in their condition. This phenomenon is commonly called the placebo effect.
A group of doctors was interested in comparing the effectiveness of placebo pills (made of sugar) and real pills in treating migraines. They randomly assigned a group of 300 patients suffering from migraines into two groups. One group was given a real pill and the other was given a placebo. Both groups were told which kind of pill they got.
Before taking the pills, and a day afterwards, the patients were asked to fill out questionnaires regarding their condition. Then, the doctors analyzed the overall changes in questionnaires for each group and compared them.

What type of statistical study did the doctors use?
A. Sample Study
B. Experiment
C. Observational Study

Is the study appropriate for the statistical questions it's supposed to answer?
A. Yes, because the patients filled the same questionnaire before and after taking the pills.
B. No, because telling patients about the pills introduces bias.
C. Yes, because the patients were randomized between the two groups.
D. No, because we don’t know how effective the real pills are.