Data and Uncertanty Flashcards
What is a measurement?
A process of experimentally obtaining the value of a quantity
The quantity that we intend to measure is called measurand.
What is a measurand?
The quantity that we intend to measure
What does the result of a measurement consist of?
A collection of quantitative data that describes a property of an object or event
What is the aim of a measurement?
To obtain the true value of the measurand
True or False: The perfect measurement exists.
False
What is uncertainty in measurement?
The inherent limitation in obtaining the true value of the measurand
What causes measurement result values to differ?
Error
What are the two types of error in measurements?
- Systematic error
- Random error
What does systematic error do to measurement results?
Shifts all measurement’s result values in a systematic way
What is random error?
Distributes individual data from the same measurement’s result in an unpredictable way
Define accuracy in measurement.
Closeness of the measurements to a specific value
Define precision in measurement.
Closeness of the measurements to each other
What is the relationship between accuracy and systematic errors?
Accuracy describes systematic errors and statistical bias
What does ISO define as accuracy?
A combination of both random and systematic observational error
What affects the precision of repeated measurements?
The number of divisions on the scale of the measuring device
What is bias in measurement?
The difference between the average value of the result and the accepted true value
Define repeatability in measurements.
Precision determined under the same methods and equipment by the same operator
Define reproducibility in measurements.
Precision determined under the same methods but different equipment by different operators
What is total error in measurement?
A combination of both systematic error and random error
Define trueness in measurement.
Closeness of agreement between the average value from tests and the accepted true value
What largely affects trueness?
Systematic error
What largely affects precision?
Random error
What is the expression of the lack of error in measurement?
Accuracy
What does uncertainty characterize in measurement?
The range of values within which the true value is asserted to lie with some level of confidence
