Repeatability

It is a measure of precision. It is the «variation due to the measuring device. It is the variation observed when the same operator measures the same part repeatedly with the same device [1].» It «is similar to uniformity except that it deals with how consistent a particular sensor is against itself. It can be used to describe the ability of a sensor to provide the same result, under the same circumstances, over and over again [2].»

Bibliographic references:

[1] Reliawiki. 2017. Measurement System Analysis. [online] Available at: <https://reliawiki.org/index.php/Measurement_System_Analysis> [Accessed 20 February 2022].

[2] Apogeeinstruments.com. 2022. Uniformity, Repeatability, Stability, and Accuracy. [online] Available at: <https://www.apogeeinstruments.com/uniformity-repeatability-stability-and-accuracy/> [Accessed 20 February 2022].

Stability

It is «a measure of how the accuracy and precision of the system perform over time [1].»

[1]

«Stability deals with the degree to which sensor characteristics remain constant over time. Changes in stability, also known as drift, can be due to components aging, decrease in sensitivity of components, and/or a change in the signal to noise ratio, etc [2].»

Bibliographic references:

[1] Reliawiki. 2017. Measurement System Analysis. [online] Available at: <https://reliawiki.org/index.php/Measurement_System_Analysis> [Accessed 20 February 2022].

[2] Apogeeinstruments.com. 2022. Uniformity, Repeatability, Stability, and Accuracy. [online] Available at: <https://www.apogeeinstruments.com/uniformity-repeatability-stability-and-accuracy/> [Accessed 20 February 2022].

Precision

«Precision describes the variation you see when you measure the same part repeatedly with the same device. It includes the following two types of variation:

• Repeatability
• Reproducibility: variation due to the operators and the interaction between operator and part. It is the variation of the bias observed when different operators measure the same parts using the same device.»
  

Bibliographic reference: Reliawiki. 2017. Measurement System Analysis. [online] Available at: <https://reliawiki.org/index.php/Measurement_System_Analysis> [Accessed 20 February 2022].

Accuracy

«Accuracy describes the difference between the measurement and the actual value of the part that is measured. It includes:

• Bias: a measure of the difference between the true value and the observed value of a part. If the “true” value is unknown, it can be calculated by averaging several measurements with the most accurate measuring equipment available.
• Linearity: a measure of how the size of the part affects the bias of a measurement system. It is the difference in the observed bias values through the expected range of measurement [1].»

  

  [1]

It is «analogous to uncertainty relative to a reference, is in its simplest terms the difference between measured and “true” values [2].»

Bibliographic references:

[1] Reliawiki. 2017. Measurement System Analysis. [online] Available at: <https://reliawiki.org/index.php/Measurement_System_Analysis> [Accessed 20 February 2022].

[2] Apogeeinstruments.com. 2022. Uniformity, Repeatability, Stability, and Accuracy. [online] Available at: <https://www.apogeeinstruments.com/uniformity-repeatability-stability-and-accuracy/> [Accessed 20 February 2022].

Survey about a controversial breast cancer clinical case

An anonymous 9 short questions survey about a controversial breast cancer clinical case. For academic records.

Link: https://docs.google.com/forms/d/e/1FAIpQLSeZh6FqosXFlcJEDyfSHttuKkLGw18QC2rWav1HI8CwTPdzvA/viewform?vc=0&c=0&w=1&flr=0.