What is Error, types and source of error

Measuring instruments

Error and types of error- Error is the deviation of the measured value from the desired value. It is also called as absolute error.

If          Yn=desired value

Xn= measured value

e=absolute error

Then e can be defined as        e= Yn Xn

Types of error-

Error can  be categorized into 3 types.

  1. Gross error
  2. Systematic error
  3. Random error

Gross error-

These errors are created by human mistake in reading or using an instrument and creating and recording the observation for the measurement.

Ex- Improper use of instrument.

Systematic error-

  1. Instrumental error-

Due to inherent measurement from an instrument and due to the mechanical structure of the instrument, this kind of error occurred.

Ex- Spring tension, friction, loading effect.

  1. Environmental error-

It occurs due to different weather condition external to the instrument such as weather,  temperature, humidity, magnetic field, electric field.

  1. Observational error-

It occurs due to observer (Person taking reading). The most common type of observer error is parallax error which is introduced due to the faulty reading of meter scale.

Random error-

Random error occurs due to the unknown causes. If all the kinds of error has been resolved any error remains with the instruments or affect the instrument is called random error. It is generally small and follows the law of probability. This error can be calculated mathematically. If the number of observation is increased the random error can be reduced.

Source of error-

  1. Poor design of the equipment.
  2. Insufficient knowledge of process parameter and design condition.
  3. Poor maintenance of the equipment.
  4. Certain design limitation.
  5. Person observing or taking the reading.


Also Read- Different methods of measurement

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