3.2 Principles of Measurement - Principles of Measurement
Key Concepts
- Accuracy
- Precision
- Sensitivity
Accuracy
Accuracy refers to how close the measured value is to the true or accepted value. It is a measure of the correctness of a measurement. High accuracy means the measurement is very close to the actual value.
Example: If a thermometer reads 98.6°F when measuring a standard temperature of 98.6°F, it is highly accurate. However, if it reads 99.5°F, it is less accurate.
Precision
Precision refers to the consistency of repeated measurements. It indicates how close the measurements are to each other, regardless of whether they are close to the true value. High precision means the measurements are very consistent.
Example: If you measure the length of a table five times and get readings of 6.02 feet, 6.03 feet, 6.02 feet, 6.03 feet, and 6.02 feet, the measurements are precise because they are very close to each other.
Sensitivity
Sensitivity refers to the smallest change in the measured quantity that the instrument can detect. It is a measure of how responsive the instrument is to changes in the quantity being measured. High sensitivity means the instrument can detect very small changes.
Example: A sensitive thermometer can detect a change in temperature as small as 0.01°F. This high sensitivity allows it to measure very slight temperature variations accurately.