<qa>  What was the primary outcome measure of the Hamilton Depression Rating Scale?We examined efficacy and safety of one specific cranial electrical stimulator CES device at a fixed setting in subjects with treatment-resistant major depressive disorder MDD. Thirty subjects with MDD and inadequate response to standard antidepressants were randomized to 3 weeks of treatment with CES 1550015000 Hz, symmetrical rectangular biphasic current of 1-4 mAmp, 40 Volts or sham CES device off for 20 minutes, 5 days per week. The primary outcome measure was improvement in the 17-item Hamilton Depression Rating Scale HAM-D-17. Adverse effects AEs were assessed using the Patient Related Inventory of Side Effects PRISE. We hypothesized that subjects who received active as opposed to sham CES would have a significantly greater improvement in their depression symptoms. Due to the small sample, we could not hypothesize an effect size, but would calculate one to determine signal strength to guide the design of a larger, more rigorous study. As an exploratory aim, we also examined whether CES would benefit sleep. 