Types of errors in measurement

No measuring instrument can indicate the exact value of measuring quantity. In the practical world, errors come with measuring instruments. There is a variety of errors in measuring instruments.

Errors are nothing but the difference between the true value and the measured value of the unknown quantity (measurand). And errors can be minute or huge.

Remember to minimize errors in the instruments.

Error in measurement

Types of errors in measurement are following:

Gross error

Gross errors are errors caused by humans. Mistake in observing or reading instruments and recording and calculating results.

Systematic error

These errors either remain constant or change according to a definite law on repeated measurement. Proper correction or calibration of instruments can effectively eliminate these errors.

Systematic error is further classified into 3 categories:

Environmental error

Different kinds of measurement instruments are applied for various purposes in different conditions. An instrument tested and calibrated in different conditions and operating under different conditions can produce severe error in the instruments.

Mostly temperature difference is the biggest cause of error under this category. Some of the other environmental changes that can cause errors in the instrument are humidity, altitude, dust, gravity, the earth’s magnetic field, and many more.

The following precautions are effective for eliminating the errors:

  1. Use the instrument under the same temperature.
  2. Apply techniques to reduce or eliminate the effects of the errors.

Observational error

This type of error occurs when the observer makes an error during reading. Parallax error comes under this category.

Instrumental error

Measuring instruments comes with inherent instrumental errors because of their operation or construction.

These are reasons for instrumental errors:

  • Inherent shortcomings in the instruments: Mechanical structure or some components of the instruments may cause an error. Eg. the spring used in devices becomes weak, the instrument always reads high.
  • Misuse of instruments: Mishandling of measuring instruments can become a reason for the error.

Random error

Random errors are seen during an experiment, the results obtained are different for the same quantity when measured repeatedly.

You can minimize the random effect by obtaining results many times and calculating the mean value of the results.

Quick summary

  • 3 types of error in measurement instruments are gross error, random error, and systematic error.

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