What is the true value of a measurement?
(The true value is sometimes also referred to as the measured value, however this term will be avoided in this text to avoid any possible confusion with the measurement value) The quality of a measurement can be described using terms such as uncertainty, precision, error and accuracy.
Is it possible for a measurement to be wrong?
We must appreciate that it is possible for poor quality measurements to be taken that produce measurement values that do not adequately reflect the true value. (The true value is sometimes also referred to as the measured value, however this term will be avoided in this text to avoid any possible confusion with the measurement value)
Is it possible to take a perfect measurement?
It is impossible to take a perfect measurement i.e. one that would give an exact true value for the property being measured. In practice the best we can do is to determine the upper and lower limits of a range of values within which the true value lies. (For example we may determine that the length of an object is somewhere between 5mm and 6mm).
How can we determine the range of a given value?
In practice the best we can do is to determine the upper and lower limits of a range of values within which the true value lies. (For example we may determine that the length of an object is somewhere between 5mm and 6mm). We call this range of values an uncertainty interval (or sometimes simple the uncertainty ).
What is the difference between measurement value and true value?
The measurement value (which is sometimes referred to simply as the measurement) is the value given by a measuring instrument and the true value is the actual value of the property being measured.
What is accuracy in property measurement?
Accuracy is a description of how close the measurement value is to the true value of the property being measured. (The smaller the error the more accurate the measurement value will be).
What is measurement error?
An error in a measurement is simply any difference between the measurement value and the true value. (It is true that poor measurement skills can introduce or increase errors in measurement values, but errors will be present in any measurement regardless of how skilfully it is taken.
Why is it important to measure the dimensions of an object?
metals expand and contract as the temperature changes, the dimensions of an object may be measured when it is being subjected to some stress or strain which will compress or stretch the object etc. Therefore it is often important to measure ...
What is precision measurement?
Precision is a description of how exact the measurement value is. It depends on the uncertainty in the measurement, the smaller the uncertainty is then the more precise the measurement value is.
