1. Palermo – April 26, 2014 Controlling the quality of diagnostic tests E. Bravi

2. 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.

3. Palermo – April 26, 2014 Precise and accurate Precise Accurate Neither precise, nor accurate Precision and accuracy

4. 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.

5. 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

6. 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

7. 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

8. Palermo – April 26, 2014

10. How to report results

11. 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

12. 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 #

13. Palermo – April 26, 2014 Questions? Thanks for your attention