A researcher is trying to develop a treatment for a new viral disease. He recruits 100 patients who have the disease and randomly assigns them to two groups (50 subjects in each group). One group gets the new anti-viral drug and the other group gets an inactive placebo. He then monitors the severity of their condition for the next week by counting the number symptoms they display each day and creates a total symptom summary score.

 a.What type of research design did the researcher use? 

b.What is the independent variable and the dependent variable? 

c.Is this a good or bad design for making a causal conclusion, i.e., the conclusion that independent variable causes the dependent variable? Be specific with what aspect of the study (described above) makes it good or bad.