Accuracy of Measurements:
The purpose of measurement is to determine the true dimensions of a part. But no measurement can be made absolutely accurate. There is always some error. The amount of error depends upon the following factors:
- The accuracy and design of the measuring instrument
- The skill of the operator
- Method adopted for measurement
- Temperature variations
- Elastic deformation of the part or instrument etc.
Thus, the true dimension of the part cannot be determined but can only by approximate. The agreement of the measured value with the true value of the measured quantity is called accuracy.
If the measurement of dimensions of a part approximates very closely to the true value of that dimension, it is said to be accurate. Thus the term accuracy denotes the closeness of the measured value with the true value.
The difference between the measured value and the true value is the error of measurement. The lesser the error, more is the accuracy.