Mymathlab homework answers

In a study designed to test the effectiveness of a medication as a treatment for lower back​ pain, 1643 patients were randomly assigned to one of three​ groups: (1) the 547 subjects in the placebo group were given pills containing no​ medication; (2) 550 subjects were in a group given pills with the medication taken at regular​ intervals; (3) 546 subjects were in a group given pills with the medication to be taken when needed for pain relief. In what specific way was replication applied in the​ study?