Journal: Annals of Laboratory Medicine

Article Title: Practical Considerations for Clinical Laboratories in Top-down Approach for Assessing the Measurement Uncertainty of Clinical Chemistry Analytes

doi: 10.3343/alm.2022.42.6.630

Figure Lengend Snippet: Schematic illustration of MU estimation by different calculation methods. (i) Total uncertainty ( u tot =s(x), SD) was calculated regardless of reagent lot changes, according to equation (1). (ii) IQC values before and after a reagent lot change were collected separately by lot number, and u Rw calculated in each data subgroup were combined to obtain the overall uncertainty (subgrouping uncertainty, u sub = s pooled (x), pooled sample SD for x organized into subgroups), according to equation (2). Abbreviations: QC, quality control; x, measurand quantity value for a measurement; x̄, mean value of a measurand; xi, ith member of a group of values (e.g., repeated measurements of a sample); n, total number of values; ni, number of values in the ith group; m, number of groups of values.

Article Snippet: We used a single chemistry measurement system (Cobas 8000 c702; Roche Diagnostics, Rotkreuz, Switzerland) and two concentration levels of IQC materials (Lyphochek Assayed Chemistry Control Levels 1 and 2; Bio-Rad, Hercules, CA, USA), including multiple reagent lots during the study period (mean, 3.14; range, 2-4).

Techniques: Control

Journal: Annals of Laboratory Medicine

Article Title: Practical Considerations for Clinical Laboratories in Top-down Approach for Assessing the Measurement Uncertainty of Clinical Chemistry Analytes

doi: 10.3343/alm.2022.42.6.630

Figure Lengend Snippet: Schematic illustration of reagent lot change simulation using artificial IQC data. (A) Process of generating baseline and shifted artificial IQC datasets. (B) MU estimation with the generated datasets by different calculation methods. Abbreviations: IQC, internal quality control; MU, measurement uncertainty; m 0–10 , arithmetic mean of baseline and shifted datasets; u tot , standard uncertainty calculated regardless of a reagent lot change; u sub , combined uncertainty calculated using values obtained from each subgroup; u base , standard uncertainty of the baseline data; u shift , standard uncertainty of the shifted data; x, measurand quantity value; n, total number of values; ni, number of values in the ith group; m, number of groups of values.

Article Snippet: We used a single chemistry measurement system (Cobas 8000 c702; Roche Diagnostics, Rotkreuz, Switzerland) and two concentration levels of IQC materials (Lyphochek Assayed Chemistry Control Levels 1 and 2; Bio-Rad, Hercules, CA, USA), including multiple reagent lots during the study period (mean, 3.14; range, 2-4).

Techniques: Generated, Control