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. Variance The values represent the variance of a set of observations made over a time interval. Variance computed using the unbiased formula 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