To show that the antidepressant effect of quetiapine 50 mg/day was not due to its sleep-inducing properties, the researchers will conduct a one-sided test of proportions comparing modified MADRS response rates between the quetiapine 50 mg/day and placebo groups (Analysis B). Again, the outcome of interest will be the presence of a positive MADRS response at any time point after baseline (i.e., Day 4, Week 1, Week 2, Week 4, and Week 6). The insomnia grouping variable does not need to be used in this analysis because the modified MADRS response rates do not include a "reduced sleep" item, and if there is significantly higher modified MADRS response rates in the quetiapine group, one can reasonably conclude that the antidepressant effect of low-dose quetiapine was not due to its ability to induce sleep in participates who were experiencing insomnia (there are no other sleep items on the MADRS). Analysis B also provides an alternate analysis strategy for understanding the role of sleep improvement in the efficacy of low-dose quetiapine should the researchers be unable to generate a meaningful insomnia grouping variable to be used in