More important, in both analyses, the mean difference between drug and placebo was less than two points on the HAM-D. The HAM-D is a 17-item scale on which people can score from 0 to 53 points, depending on how depressed they are. A six-point difference can be obtained just by changes in sleep patterns, with no change in any other symptom of depression. So the 1.8 difference that we found between drug and placebo was very small indeed – small enough to be clinically insignificant. But you don’t have to take my word for how small this difference is. The National Institute for Health and Care Excellence (NICE), which drafts treatment guidelines for the National Health Service in the United Kingdom, has established a three-point difference between drug and placebo on the HAM-D as a criterion of clinical significance (NICE, 2004). Thus, when published and unpublished data are combined, they fail to show a clinically significant advantage for antidepressant medication over inert placebo. - www.ncbi.nlm.nih.gov