# Test and Measurement World

## Test and Measurement World Terminology Section

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## Systematic Error vs Random Error | Difference between Systematic Error and Random Error

This page compares Systematic Error vs Random Error and mentions difference between Systematic Error and Random Error.

### Systematic Error

Systematic errors are regularly repetitive in nature. They are of constant and similar form. They result from improper conditions or procedures that are consistent in action. Out of the systematic errors all except the personal error varies from individual to individual depending on the personality of observer. Other systematic errors can be controlled in magnitude as well as in sense. If properly analyzed they can be determined and reduced. Hence, these are also called as controllable errors.

Systematic errors include calibration errors, Environmental Errors (Ambient or Atmospheric conditions), Stylus Pressure, and Avoidable Errors.

### Random Error

Random errors are non-consistent. They occur randomly and are accidental in nature. Such errors are inherent in the measuring system. It is difficult to eliminate such errors. Their specific cause, magnitudes and source cannot be determined from the knowledge of measuring system or conditions of measurement.

The possible sources of such errors are as follows.
• Small variations in the position of setting standard and work piece.
• Slight displacement of lever joints of measuring instruments.
• Operator error in scale reading.
• Fluctuations in the friction of measuring instrument etc.

### Difference between Systematic Error and Random Error

Following table summarizes difference between systematic error and random error with respect to various parameters of comparison.

Systematic Error Random Error
These errors are repetitive in nature and are of constant and similar form These are non-consistent. The sources giving rise to such errors are random.
These errors result from improper conditions or procedures that are consistent in action. Such errors are inherent in the measuring system or measuring instruments
Except personal errors, all other systematic errors can be controlled in magnitude and sense. Specific causes, magnitudes and sense of these errors cannot be determined from the knowledge of measuring system or condition.
If properly analyzed these can be determined and reduced or eliminated. These errors cannot be eliminated, but the results obtained can be corrected.
These include calibration errors, variation in contact pressure, variation in atmospheric conditions, parallax errors, misalignment errors etc. These include errors caused due to variation in position of setting standard and work-piece, errors due to displacement of lever joints of instruments, errors resulting from backlash, friction etc.