A computer-implemented method of determining sigma of a clinical diagnostic process, comprising: acquiring specimen data from a plurality of laboratory instruments; identifying a concentration of each specimen of said specimen data; evaluating said specimen data and determining an analytical standard deviation for a plurality of said specimen data; acquiring patient analyte values; assigning standard deviations to said patient analyte values based on said specimen data analytical standard deviations, wherein said assigning standard deviations to said patient analyte values comprises: determining a concentration of each patient analyte of said patient analyte values; comparing said concentrations of said patient analyte values to concentrations of said specimen data; and assigning a standard deviation to said patient analyte values from specimen data having a corresponding concentration; computing a single sigma-metric from said assigned standard deviations, said sigma-metric representing a sigma for said clinical diagnostic process, wherein a sigma value for each patient is estimated by computing the ratio of a Total Allowable Error goal for each patent analyte value divided by the standard deviation for the patient analyte value and the sigma-metric is calculated by adding the sigma values for each patient analyte value and dividing that sum by the total number of patient analyte values; and reporting said sigma-metric to a user of at least one of said plurality of laboratory instruments. acquiring specimen data from a plurality of laboratory instruments; identifying a concentration of each specimen of said specimen data; evaluating said specimen data and determining an analytical standard deviation for a plurality of said specimen data; acquiring patient analyte values; assigning standard deviations to said patient analyte values based on said specimen data analytical standard deviations, wherein said assigning standard deviations to said patient analyte values comprises: determining a concentration of each patient analyte of said patient analyte values; comparing said concentrations of said patient analyte values to concentrations of said specimen data; and assigning a standard deviation to said patient analyte values from specimen data having a corresponding concentration; determining a concentration of each patient analyte of said patient analyte values; comparing said concentrations of said patient analyte values to concentrations of said specimen data; and assigning a standard deviation to said patient analyte values from specimen data having a corresponding concentration; computing a single sigma-metric from said assigned standard deviations, said sigma-metric representing a sigma for said clinical diagnostic process, wherein a sigma value for each patient is estimated by computing the ratio of a Total Allowable Error goal for each patent analyte value divided by the standard deviation for the patient analyte value and the sigma-metric is calculated by adding the sigma values for each patient analyte value and dividing that sum by the total number of patient analyte values; and reporting said sigma-metric to a user of at least one of said plurality of laboratory instruments.