There are various kinds of Error in measurement. In this note, Poly Notes Hub is sharing knowledge about errors and Types of errors like Gross, Systematic, Instrumental, Environmental, and Observational Errors.
Author Name: Arun Paul.
What is Error?
Error may be expressed either as absolute or as percentage of error. Absolute error may be defined as the difference between the expected value of the variable and measured value of the variable, or
e = Yn – Xn
where,
e = Error or Absolute Error
Yn = Expected Value
Xn = Measured Value
Types of Errors in Measurement ( Static Error )
The static error of a measuring instrument is the numerical difference between the true value of a quantity and its value as obtained by measurement, i.e. repeated measurement of the same quantity gives different indications. Static errors are categorized as gross errors or human errors, systemic errors, and random errors.
Below, we discusses about different types of Error in Measurement –
Gross Errors
These are mainly due to human mistakes in reading or in using instruments or errors in recording observations. Errors may also occur due to incorrect adjustment of instruments and computational mistakes. These errors can’t be treated mathematically.
The complete elimination of gross errors is not possible, but one can minimize them. Some errors are easily detected while others may be elusive.
Systematic Errors
These occur due to shortcomings of the instrument, such as defective or worn parts, aging, or the effects of the environment on the instrument.
These errors are sometimes referred to as bias, and they influence all measurements of a quantity alike. A constant uniform deviation of the operation of an instrument is known as a systematic error. There are three types of systematic error – 1) Instrumental, 2) Environmental, and 3) Observational.
1. Instrumental Errors
Instrumental Errors are inherent in measuring instruments, because of their mechanical structure. For example, in the D’ Arsonval movement, friction in the bearings of various moving components, irregular spring tensions, stretching of the spring, or reduction in tension due to improper handling or overloading of the instrument.
2. Environmental Errors
Environmental Errors are due to connections external to the measuring device, including conditions in the area surrounding the instrument, such as the effects of change in temperature, humidity, barometric pressure, or of magnetic or electrostatic fields.
3. Observational Errors
Observational Errors are errors introduced by the observer. The most common error is the parallax error introduced in reading a meter scale, and the error of estimation when obtaining a reading from a meter scale.
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