For many nonresponders, the switch resulted in clinically as well as statistically significant improvements. Of the 207 nonresponders at the end of the first 12 weeks, 168 switched medications (51 from imipramine to sertraline and 117 from sertraline to imipramine). The two "switch groups," according to the authors, "did not differ significantly on any relevant characteristic." An acceptable response to medication was defined as a final CGI-I score of 1 or 2, a reduction of at least 50 percent on the final Ham-D score resulting in a score of 15 or lower, and a CGI-S score of 3 or lower. Full remission was defined as a final Ham-D of 7 or lower, and a CGI-I score of 2 or lower.