Posted by Sten Westgard, MS
From Dr. Carmen Ricos, on behalf o the SEQC-Analytical Quality Commission:
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
We want your control chart data!
We've always had an "open door" policy on the website, welcoming your questions and your data. At times, we may not be so explicit in inviting you to contact us with your observations, comments, inquiries, and frustrations, but we do want to hear from you.
Now, we're asking for a more specific set of data from you - for your problem methods, show us a few months of QC data, ideally with notations such as new control lot, new reagent, recalibration, etc.
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Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
By Sten Westgard, MS
While Dr. Westgard has spoken about the "War of Words" between Uncertainty and Total Error in several essays (here, here and here most recently), we thought readers might want an additional perspective on the issue.
Dietmar Stockl, an expert in statistics and laboratory quality control from across the Atlantic, graces us with an guest essay on the calculation, use, benefits and limitations of measurement uncertainty: Time to Engage in Measurement Uncertainty. Dr. Stockl provides an in-depth look at uncertainty concepts and calculations, as well as a moderate viewpoint on the use of the term. He views both Total Error and Measurement Uncertainty are useful concepts and believes there is room in the world for both of them. It's not necessary for one term to eliminate the other.
Not so coincidentally, a colleague of Dr. Stockl's, Linda Thienpont, has a letter in Clinical Chemistry talking about the attempt to incorporate bias into the calculation of measurement uncertainty. If bias can be thrown into the uncertainty calculations, a case could be made that Total Error is no longer necessary. Dr. Thienpont points out that slipping bias into the uncertainty calculations is not a good idea and can lead to distorted results. She concludes that bias must remain separate from uncertainty calculations, which means another approach like Total Error is required to account for it.
See more at Thienpont LM. Calculation of measurement uncertainty-Why bias should be treated separately. Clin Chem 2008;54:1587 (subscription required) -----
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS<
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard
This month, Dr. Westgard was teaching his spring semester class for the University of Wisconsin Medical Technology school. He likes to use recently published papers in the scientific literature as a way to relate his lessons to things happening in the "real world" of the laboratory.
This semester, he has written up a number of lessons covering HbA1c methods, performance, and quality requirements based on the article in Clinical Chemistry, Few Point-of-Care Hemoglobin A1c Assay Methods Meet Clinical Needs, by David E. Bruns1 and James C. Boyd and a study by Lenters-Westra and Slingerland (Six out of eight hemoglobin A1c point-of care instruments do not meet the generally accepted analytical performance criteria. Clin Chem 2010;56:44 –52.)
For your convenience, here are the lessons in order...
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