While dealing with any kind of measurements, it is important to identify the possible sources of error. It helps to maintain the accuracy of physical measurement in both fields and labs. There are mainly three possible sources of errors.


The imperfection or faulty adjustment of the measurement instrument may cause errors. Such errors, produced from the equipment, is known as instrumental error. Example: a long or short tape, an angle measurement instrument without proper adjustment.


Error may also arise due to imperfection of human sight in observation and of touch in manipulating instruments. These man made errors are known as personal error. Example: Taking wrong level reading, taking wrong reading of an angle of circle of a theodolite.


Variation of natural phenomena is also a possible source of error. Variation of temperature, humidity, gravity, wind, refraction, magnetic declination etc. are most common natural phenomena which may cause measurement errors. If they are not properly observed while taking measurements, the results will be incorrect. Example: Length error of tape or chain due to temperature change.


When any surveying such as land survey, topographical survey, building survey, structural survey, boundary survey, property survey etc. or any other measurements are done these possible sources of errors should be highly considered for an accurate measurement. All the surveying tools and surveying equipment should be selected in such that they are free from any errors. The surveyor’s should be careful during taking measurements. They should make proper adjustment for any natural phenomena occurs.