Table of Contents
The observational error can be measured in two ways: accuracy and precision. Precision is defined as how near or far apart a set of measurements are from their true value, whilst accuracy is defined as how close or far apart the measurements are from each other. In other words, precision is a measure of statistical variability that describes random errors. Accuracy can be defined in two ways: Low accuracy creates a divergence between a result and a real value; ISO calls this trueness. It is most usually a description of just systematic mistakes, a measure of statistical bias of a particular central tendency; low accuracy causes a difference between a result and a true value. Alternatively, ISO defines accuracy as a combination of both random and systematic observational error, implying that high accuracy necessitates both high precision and high trueness.
The terms accuracy, validity, and constant error are used interchangeably in psychometrics and psychophysics. Precision is often used interchangeably with the terms “reliability” and “variable error.” Experimentation or behaviour correlation is used to determine the validity of a measurement instrument or psychological test. When evaluating correct models in logic simulation, a typical mistake is to compare a logic simulation model to a transistor circuit simulation model. This is a comparison of precision differences rather than accuracy. Precision is measured in terms of detail, whereas accuracy is judged in terms of actuality.
A brief outline
The concept of “accuracy” is independent of “precision” in the first, more frequent definition above, so a piece of data might be stated to be accurate, precise, both, or neither. In simpler terms, if the average of a sample population or set of data points from repeated measurements of the same quantity is close to the true value of the quantity being measured, the sample or set is said to be accurate, and the set is said to be precise if the standard deviation is relatively small. The degree of closeness of measures of a quantity to that number’s real value is the accuracy of a measurement system in science and engineering.
Important concepts
Accuracy
Accuracy refers to an instrument’s capacity to measure a precise value. In other terms, it refers to how close a measured value is to a genuine or standard value. Small readings are used to achieve accuracy. The little reading decreases the calculation’s inaccuracy. The system’s accuracy can be divided into three categories:
Accuracy of points
Point accuracy refers to the instrument’s precision just at a single point on its scale. It is vital to remember that this accuracy provides no information regarding the instrument’s overall accuracy.
Accuracy expressed as a percentage of the scale range
A measurement’s precision is determined by the uniform scale range.
E.g., Consider a thermometer with a temperature range of up to 500 degrees Celsius. The thermometer has a precision of 0.5, which means that a 0.5 percent change in the instrument’s value is insignificant. A high-value error is defined as a reading that is more or less than 0.5oC.
Percentage of True Value Accuracy
This form of instrument accuracy is determined by comparing the measured value to their true value. The instruments’ accuracy is ignored up to 0.5 percent of the genuine value.
Precision
A substance’s precision can be measured by how close two or more measurements are to each other. For example, if you weigh a substance five times and get the same result each time, then you have very precise measurements, but not necessarily accurate ones.
Precision is not the same as accuracy. The following example demonstrates how you can be precise but inaccurate, and vice versa. Precision can be broken down into the following categories:
Repeatability
The variation occurs when the conditions are kept constant and multiple measurements are done over a short period of time.
Reproducibility
Variation occurs when the same measuring technique is used by different instruments and operators over longer periods of time.
Conclusion
The degree of similarity between measurement and its true value is known as accuracy. The degree to which successive observations under the same conditions are constant is known as precision.
Examples of Precision and Accuracy
Imagine a football player aiming at the goal. This is a fantastic comparison for grasping accuracy and precision. A player is deemed to be accurate if he shoots into the goal. A football player who hits the same goalpost over and over is precise but not accurate. As a result, if a football player smashes the ball all over the place but still scores, he can be accurate without being exact. Whether he scores or not, a precise player will consistently hit the ball to the same position. A football player who is precise and accurate will not only aim at a specific location but will also score the goal.
Additional Illustrations
- The measurement is said to be accurate if the weather heat reads 28 °C outdoors and it is 28 °C outside. The measurement is also exact if the thermometer consistently records the same temperature over numerous days.
- When you measure the mass of a 20 kg body and obtain 17.4,17,17.3 and 17.1, your weighing scale is exact but not very accurate. The values of 19.8, 20.5, 21.0, and 19.6 on your scale are more accurate than the original balance, but not particularly precise.
Significance of precision and accuracy in IIT JEE exam
One of the most significant chapters in the IIT JEE syllabus is Dimensions and Measurement. On the exam, students usually get 2-3 questions from this chapter. If aspirants complete last year’s examinations, they will see that concepts from this chapter are also used to tackle longer questions. In the 2018 JEE test, two questions from this area precision and accuracy received three points each, resulting in a bonus of six points, hence applicants are advised to study the chapter completely.
FAQs
The degree to which repeated observations under the same circumstances are unchanged is known as precision.
Error is defined as the discrepancy between the actual and measured values.
The proximity of a measured value to a standard or genuine value is referred to as accuracy. What does precision imply?
What does it mean to make a mistake?
What does it mean to be accurate?
