Accuracy and Precision
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- Date Submitted: 04/30/2011 01:00 PM
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Title
Accuracy and Precision
Introduction
We can never say a measurement is perfect. All measurements have some error associated with them. The best we can do is to come as close as possible within the limitations of the measuring instruments. In microbiology, two terms often used somewhat interchangeably to describe measurement errors are precision and accuracy. The Accuracy of a measurement system is the degree of closeness of measurements from a standard or true value of the quantity being measured. The Precision of a measurement system, can be called repeatability or reproducibility, is the degree to which repeated measurements under the same conditions get the same results each time.
Figure [ 1 ]: Accuracy indicates proximity of measurement results to the true value, precision to the repeatability or reproducibility of the measurement
It was asked in this practical to understand the meaning of accuracy when working with numbers of organisms and also to explain why it is important to be accurate and precise within a microbiological practical.
Discussion
A measurement system is called valid if it is both accurate and precise. Failure to achieve either accuracy or precision requirements is enough to constitute a failed test or calibration. Calibration is the act of checking or adjusting (by comparison with a standard) the accuracy of a measuring instrument. The precision instruments that can be used are many and for different purposes as well. In microbiology the most used ones are: micropipettes, balances/scales and incubators, just to give an example.
There are high standards pre-established to make sure that calibrated equipment meets accuracy and precision requirements. When these requirements are not met actions have to be taken to determine if there was any adverse effect on the product quality. The faulty equipment would have to be either repaired and/or recalibrated and three particular areas would have to be checked: the product...
Accuracy and Precision
Introduction
We can never say a measurement is perfect. All measurements have some error associated with them. The best we can do is to come as close as possible within the limitations of the measuring instruments. In microbiology, two terms often used somewhat interchangeably to describe measurement errors are precision and accuracy. The Accuracy of a measurement system is the degree of closeness of measurements from a standard or true value of the quantity being measured. The Precision of a measurement system, can be called repeatability or reproducibility, is the degree to which repeated measurements under the same conditions get the same results each time.
Figure [ 1 ]: Accuracy indicates proximity of measurement results to the true value, precision to the repeatability or reproducibility of the measurement
It was asked in this practical to understand the meaning of accuracy when working with numbers of organisms and also to explain why it is important to be accurate and precise within a microbiological practical.
Discussion
A measurement system is called valid if it is both accurate and precise. Failure to achieve either accuracy or precision requirements is enough to constitute a failed test or calibration. Calibration is the act of checking or adjusting (by comparison with a standard) the accuracy of a measuring instrument. The precision instruments that can be used are many and for different purposes as well. In microbiology the most used ones are: micropipettes, balances/scales and incubators, just to give an example.
There are high standards pre-established to make sure that calibrated equipment meets accuracy and precision requirements. When these requirements are not met actions have to be taken to determine if there was any adverse effect on the product quality. The faulty equipment would have to be either repaired and/or recalibrated and three particular areas would have to be checked: the product...