Engineering Surveying
(LSGI2961)
Lecture 3
Theory of Surveying Errors
1
, Civil Engineering Construction Mistakes
“For a civil engineer, there is no such thing as a “little mistake””
, Errors in measurement
Accuracy and Precision
Accuracy is the degree of conformity with a standard or accepted
value. (How close the measurement is to the true value)
Accuracy relates to the quality of the result.
The standard used to determine accuracy can be :
▪ An exact known value, such as the sum of the three interior angles of a plane
triangle is 180°.
▪ A value of a conventional unit as defined by a physical representation thereof,
such as the international meter.
▪ A survey or map value determined by superior methods and deemed
sufficiently near the ideal or true value to be held constant for the control of
dependent operations.
, Errors in measurement
Accuracy and Precision
Precision is the degree of refinement in the performance of an
operation (procedures and instrumentation) or in the statement of
a result. It is a measure of the uniformity or reproducibility of the
result.
Precision also called reproducibility or repeatability, the degree to
which further measurements or calculations show the same or
similar results.
Precision: Degree of perfection used in the survey
Accuracy: Degree of perfection obtained in the result.
(LSGI2961)
Lecture 3
Theory of Surveying Errors
1
, Civil Engineering Construction Mistakes
“For a civil engineer, there is no such thing as a “little mistake””
, Errors in measurement
Accuracy and Precision
Accuracy is the degree of conformity with a standard or accepted
value. (How close the measurement is to the true value)
Accuracy relates to the quality of the result.
The standard used to determine accuracy can be :
▪ An exact known value, such as the sum of the three interior angles of a plane
triangle is 180°.
▪ A value of a conventional unit as defined by a physical representation thereof,
such as the international meter.
▪ A survey or map value determined by superior methods and deemed
sufficiently near the ideal or true value to be held constant for the control of
dependent operations.
, Errors in measurement
Accuracy and Precision
Precision is the degree of refinement in the performance of an
operation (procedures and instrumentation) or in the statement of
a result. It is a measure of the uniformity or reproducibility of the
result.
Precision also called reproducibility or repeatability, the degree to
which further measurements or calculations show the same or
similar results.
Precision: Degree of perfection used in the survey
Accuracy: Degree of perfection obtained in the result.
