errors
ERRORS IN MEASUREMENT
Errors in Measurement
Structure
2.1
Introduction
Objectives
2.2
Classification of Errors
2.2.1
Gross Errors
2.2.2
Systematic Errors
2.2.3
Random Errors
2.3
Accuracy and Precision
2.4
Calibration of the Instrument
2.5
Analysis of the Errors
2.5.1
Error Analysis on Common Sense Basis
2.5.2
Statistical Analysis of Experimental Data
2.6
Summary
2.7
Key Words
2.8
Answers to SAQs
2.1 INTRODUCTION
The measurement of a quantity is based on some International fundamental standards.
These fundamental standards are perfectly accurate, while others are derived from these.
These derived standards are not perfectly accurate in spite of all precautions. In general, measurement of any quantity is done by comparing with derived standards which themselves are not perfectly accurate. So, the error in the measurement is not only due to error in methods but also due to standards (derived) not being perfectly accurate. Thus, the measurement with 100% accuracy is not possible with any method.
Error in the measurement of a physical quantity is its deviation from actual value. If an experimenter knew the error, he or she would correct it and it would no longer be an error. In other words, the real errors in experimental data are those factors that are always vague to some extent and carry some amount of uncertainty. A reasonable definition of experimental uncertainty may be taken as the possible value the error may have. The uncertainty may vary a great deal depending upon the circumstances of the experiment. Perhaps it is better to speak of experimental uncertainty instead of experimental error because the magnitude of an error is uncertain.
At this point, we may mention some of the types of errors that cause uncertainty is an experimental in measurement. First, there can always be those gross blunders in apparatus or instrument construction which may invalidate the
Errors in Measurement
Structure
2.1
Introduction
Objectives
2.2
Classification of Errors
2.2.1
Gross Errors
2.2.2
Systematic Errors
2.2.3
Random Errors
2.3
Accuracy and Precision
2.4
Calibration of the Instrument
2.5
Analysis of the Errors
2.5.1
Error Analysis on Common Sense Basis
2.5.2
Statistical Analysis of Experimental Data
2.6
Summary
2.7
Key Words
2.8
Answers to SAQs
2.1 INTRODUCTION
The measurement of a quantity is based on some International fundamental standards.
These fundamental standards are perfectly accurate, while others are derived from these.
These derived standards are not perfectly accurate in spite of all precautions. In general, measurement of any quantity is done by comparing with derived standards which themselves are not perfectly accurate. So, the error in the measurement is not only due to error in methods but also due to standards (derived) not being perfectly accurate. Thus, the measurement with 100% accuracy is not possible with any method.
Error in the measurement of a physical quantity is its deviation from actual value. If an experimenter knew the error, he or she would correct it and it would no longer be an error. In other words, the real errors in experimental data are those factors that are always vague to some extent and carry some amount of uncertainty. A reasonable definition of experimental uncertainty may be taken as the possible value the error may have. The uncertainty may vary a great deal depending upon the circumstances of the experiment. Perhaps it is better to speak of experimental uncertainty instead of experimental error because the magnitude of an error is uncertain.
At this point, we may mention some of the types of errors that cause uncertainty is an experimental in measurement. First, there can always be those gross blunders in apparatus or instrument construction which may invalidate the