Concurrent controls parallel-group design

The design that is predominantly discussed in this book is the randomized, concurrently controlled, double-blind, parallel group design. The four descriptors in this title - randomized, double-blind, concurrently controlled, and parallel group - identify different aspects of this design. We start with the last two descriptors, parallel group and concurrently controlled, because these capture the fundamental nature of the design. We then discuss the first two descriptors, randomized and double blind. 

---