Because we used scaled values to represent measured antibody level, there is no recognized unit with which to describe increasing or decreasing levels. In this case, we chose the SD as the unit of measure. All results are reported as HRs for each increase of 1 SD of antibody level. This method also allows comparison between the effects of different antibody agents on schizophrenia. The SD of antibody level for the 6 agents ranged from 0.10 for HHV-6 to 0.59 for HSV-2.