ODM2 Aggregation Statistic Controlled Vocabulary ODM2 Working Group A vocabulary for describing the calculated statistic associated with recorded observations. The aggregation statistic is calculated over the time aggregation interval associated with the recorded observation. Standard deviation The values represent the standard deviation of a set of observations made over a time interval. Standard deviation computed using the unbiased formula SQRT(SUM((Xi-mean)^2)/(n-1)) are preferred. The specific formula used to compute variance can be noted in the methods description. Adapted from CUAHSI HIS DataTypeCV. See http://his.cuahsi.org/mastercvreg/edit_cv11.aspx?tbl=DataTy