Should the interaction tested in Analysis C be nonsignificant, but there be a raw proportion difference of > .10 for response rates between the melancholic and nonmelancholic groups who received quetiapine 150-300 mg/day, as a secondary analysis for Hypothesis 2, the researchers will also compare MADRS response rates between participants with melancholic depression and nonmelancholic depression who were randomly assigned to receive quetiapine with an independent-samples proportion test (Analysis D). The outcome of interest will be the presence of a positive MADRS response at any time point after baseline up until the end of Week 6. With a presumed prevalence of 30% for melancholic depression, the researchers would be able to detect a proportion difference as small as .10 (Cohen h = .20, which is "small") with 90% power (power analysis conducted with G*Power, http://www.gpower.hhu.de/en.html).