Our laboratory is participating monthly in the external QC survey of RIQAS (Randox International quality assessment scheme, Randox Laboratories, United Kingdom) from which we retrieve the TS, SDI and % Deviation results calculated from the peer group data.
We have validated quality control of our lab by calculating 3 months mean from the data of internal QC from the Advia Centaur XPT analyser data and online reports from the RIQAS (External Quality Assurance Scheme) website to establish the coefficient of variation and bias respectively, for each analyte.
Bias was taken from % of Deviation of the peer group data from results returned from RIQAS; Bias (%) = (mean of all laboratories using same instrument and method -our mean) /mean of all laboratories using same instrument and method) X 100
The inaccuracy data for the TFT parameters that is % of Deviation (Bias) from the peer group data were obtained from RIQAS online reports.
For the month of September, RIQAS results showed well performing T3 and T4 but TSH was having a very low TS; and SDI, %Deviation were outside limits.
RIQAS reports of external quality assurance allows to compare the lab results with statistically robust consensus means and identify acceptable and poor performance using fit-for-purpose performance indicators: SDI, %Deviation (Rapid assessment of concentration related biases) and Target Score (This chart provides a numerical index of performance, allowing at-a-glance assessment).
Table 1 shows the residual values defined by RIQAS,Rwp y [R.sub.Bragg], for final refinements by least squares together with the percentages of the phases.
To quantify the amorphous material by using the program RIQAS a crystalline standard (free amorphous) was added to the natural clinker in a known percentage.
Rietveld Quantitative Analysis and Whole Pattern Fitting, RIQAS, 2006.