To measure the effectiveness of a new pain reliever a group

To measure the effectiveness of a new pain reliever, a group of patients in a pain clinic are randomly chosen to receive a dose of the new medication or a placebo. In order to reduce the effect of any bias, neither the patients nor the doctors know who gets what kind of treatment. At the end of 6 weeks, all the patients were asked to rate their pain level. What type of study is described here?

a) Observational, case control                         c) Cross sectional study

b) Double blind experiment                             d) Sample survey

Solution

Answer: b) Double blind experiment     

double-blind experiment - an experimental procedure in which neither the subjects of the experiment nor the persons administering the experiment know the critical aspects of the experiment; \"a double-blind procedure is used to guard against both experimenter bias and placebo effects\"