A statistical approach was used to estimate the relative combined uncertainty (UC) by combining relative uncertainties of

imprecision (Uimp), bias (Ub) and calibrators (Uref).

Error-transformed values at the extreme limits for the allowable errors for bias and

imprecision for nonHDL demonstrate a large constant bias and a small proportional bias in relationship with the error-free nonHDL values (Figure 1).

Thus, 100 patients were modeled for 100 h with each regimen with both the hourly and every-5-min measurement schemas under 45 combinations of simulated bias and

imprecision.

showed (3), the maximum allowable bias and

imprecision are interrelated, and they can be described in the curve presented in Fig.

The

imprecision data from QC material obtained over the duration of the trial is summarized in Table 1, together with the

imprecision data obtained from duplicate testing on patient samples in the closest corresponding bin.

Data are presented as contour plots, which show the percent of insulin dosing errors as a function of increasing bias and

imprecision.

A similar study that used different modeling techniques explored the effect of assay

imprecision on the ROC area under the curve for prognosis by using cardiac troponin from the Gusto IIA trial (8).

1 is that total

imprecision and random patient interferences have been separated.

The within-run

imprecision (CV) and cardiac troponin I (cTnI) concentration pairs we derived from that study produce an SD profile that decreases slightly for cTnI concentrations of 0.

To assess the effect of increased assay

imprecision on the estimate of the AUC and the SE of the AUC, we assumed that replicate measurements by a given assay of a sample with a fixed concentration of analyte followed a gaussian distribution and that the increase in assay CV was a constant percentage value across all concentrations within the measuring range of the assay.

1 are the probabilities of at least 1 of 3 serially measured values exceeding the 99th percentile limits as a function of the cTnI concentration for the 2 different

imprecision profiles.

Imprecision was assessed in laboratories 1, 2, and 3 by use of commercial control samples, all prepared from human serum, obtained from three suppliers: Bio-Rad Laboratories BV; UTAK Laboratories Inc.