Definition: The difference between the true value and the measured value of the quantity is known as an error in measurement. The error in measurement can not be eliminated completely but it can be minimized. there are various types of errors in measurement.
Types of Errors in Measurement
Base on the nature of errors these are classified into following
1) Systematic types of error
Those errors which are confined in unidirectional either positive or negative called systematic errors.
Types of systematic errors are categorized into
- Instrumental errors: these errors arise due to defective measuring instruments or defects in the manufacturing design of the device.
- Personal errors: These errors occur in measuring instruments due to the inexperience of the observer or the person who carried out the measurements. For example – The observer reads the 81.4ºC reading while the actual reading is 31.4Cº. This happens because of oversights.
- Imperfection: These types of errors arise due to measuring instruments are not found in the perfect mod and some errors occur called imperfection errors
2) Random Errors
These types of errors occur irregularly. these errors are also called random errors because of their sign and size. these errors occur due to external causes like temperature, pressure, and wind like atmospheric conditions.
3) Least Count Error
The smallest or minimum value that can be measured by measuring instruments is called as least count. all the readings measured using measuring instruments are accurate only up to its least count. This error is associated with the resolution of the measuring device and can be minimized using high-resolution instruments. the errors as a whole are called as gross errors.
On the basis of mathematical calculations of measurements, these errors are categorized into the following types
- Absolute error: In the measurement of a physical quantity the difference between the true value and individually measured value of the quantity is called absolute error.
- Mean absolute error: The arithmetic mean of absolute errors at all measurements of a quantity is called as mean absolute error.
- Relative error: The ratio of mean absolute error to the mean value of the quantity is called relative error. also called as a fractional error. If this ratio is expressed in % then errors are called a percentage error.