Nucryst Pharmaceuticals, Inc., announced the results of its rst human trial of NPI 32101, a topical form

Nucryst Pharmaceuticals, Inc., announced the results of its first human trial of NPI 32101, a topical form of its skin ointment. A total of 225 patients diagnosed with skin irritations were randomly divided into three groups as part of a double-blind, placebo-controlled study to test the effectiveness of the new topical cream. The first group received a 0.5% cream, the second group received a 1.0% cream, and the third group received a placebo. Groups were treated twice daily for a 6-week period.
(a) What type of experimental design is this?
(b) What is the response variable in this experiment?
(c) What is the factor that is set to predetermined levels? What are the treatments?
(d) What does it mean for this study to be double-blind?
(e) What is the control group for this study?
(f ) Identify the experimental units.
(g) Draw a diagram similar to Figure 7 or 8 to illustrate the design.