palermo – april 26, 2014 controlling the quality of diagnostic tests e. bravi

Palermo – April 26, 2014

Controlling the quality of diagnostic tests

E. Bravi


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.


Precise and accurate

Precise

Accurate

Neither precise, nor accurate

Precision and accuracy


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.


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


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


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


How to report results


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


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 #


Questions?

Thanks for your attention

palermo – april 26, 2014 controlling the quality of diagnostic tests e. bravi

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