palermo – april 26, 2014 controlling the quality of diagnostic tests e. bravi
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Palermo – April 26, 2014
Controlling the quality of diagnostic tests
E. Bravi
Palermo – April 26, 2014
Precision & Accuracy
In the fields of science, engineering, industry, and statistics, the ACCURACY of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual (true) value.
The PRECISION of a measurement system, related to reproducibility and repeatability, is the degree to which repeated measurements under unchanged conditions show the same results.
Although the two words, precision and accuracy, can be synonymous in colloquial use, they are deliberately contrasted in the context of the scientific method.
Palermo – April 26, 2014
Precise and accurate
Precise
Accurate
Neither precise, nor accurate
Precision and accuracy
Palermo – April 26, 2014
Purpose of the exercise
To check how the performance of different test results may influence the follow-up of patients submitted to a Gluten Free Diet in various clinical settings.
Palermo – April 26, 2014
Materials available
7 vials containing ready-to-use samples. Samples must not be diluted Each sample has a different anti-tTG concentration Anti-tTG concentration is unknown
Palermo – April 26, 2014
Protocol
1. Each centre will be assigned a code by MediCel
2. Register data results into the provided spreadsheet
3. Complete the spreadsheet and send it back to the evaluation centre
4. The evaluation centre will provide all participants with overall and their results
Palermo – April 26, 2014
Assay Protocol
1. Allow all reagents to reach room temperature
2. Run your own assay as usual
3. Include unknown samples as ready-to-use specimens
4. Register data results into the provided spreadsheet
Palermo – April 26, 2014
Palermo – April 26, 2014
Palermo – April 26, 2014
How to report results
Palermo – April 26, 2014
Interpretation
Results will be used as follows:
All values:To generate a consensus Mean.To define acceptability range (Mean ± 2 St. Dev.)
and for each method:To calculate Mean and Standard Deviation
Palermo – April 26, 2014
Overall data - Example of graph
+2 St Dev
Mean
-2 St. Dev
* * * * * * * * * *
1 2 3 4 5 6 7 8 9 10
Cumulative Mean
* Your lab
Lab #
Palermo – April 26, 2014
Questions?
Thanks for your attention
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