What are Accuracy and Precision?

Precision and accuracy are indicators of the error of observation alongside uncertainties. Accuracy refers to how close or distant the measurements are from their actual value, and precision measures how close or dispersed measurements are or define the closeness of the measured value.

In science, the precision of measuring systems is defined as the degree of apprehension of measurements to the real value. A measurement system’s accuracy depends on repeatability and reproducibility; repeated measuring with some uncertainty and identical conditions yield identical results. While the terms precision and accuracy are the same in common usage, they are consciously contrasting in physics.

Measurement Uncertainties

The full description of the measured value must contain an estimation of the amount of confidence that is associated with the result. A clear and accurate report of the results of an experiment and its uncertainties will allow other individuals to form an opinion about what they think about the quality of the test and allow accurate comparison with similar results or a theoretical prediction. Without an estimate of uncertainty, it’s difficult to answer the most fundamental science-based question, “Does your result match a theory assumption or the results of other studies?” This is the most crucial factor to consider when deciding whether a scientific theory is proved or rejected.

Accuracy and Precision of Measurement

Science is built on observation and experimentation, that is, measurements. Accuracy refers to how close a measurement is to the right amount. For instance, let us imagine that you’re taking measurements of the length of regular computer paper. The package you purchased the paper indicates that it’s 11.0 inches wide. You can measure its length three times to get the dimensions: 11.1 inches, 11.2 inches, and 10.9 inches. These measurements are exact because they are incredibly close to the precise measurement of 11.0 inches. However, if one of the measurements was 12 inches, the experiment wouldn’t show precise results.

The accuracy of a measurement device is measured by how close the agreement is between repeat measurements (which are repeated in the same circumstances). Think about the case of measurements made on paper. The accuracy of the measurements is in the range of measured values with some uncertainty. A way to assess the accuracy of measurements is to find the variation or the range between the smallest and highest measured values. In this case, the value of the lowest was 10.9 in, and the most significant was 11.2 in. So, the measurements differed from one another only by 0.3 inches. The measurements were pretty exact because they didn’t change their value too much. However, if these values were 10.9, 11.1, and 11.9, the measurements would not be exact because there would be a significant variance from one measurement to the next.

Uncertainties in measurement

Every measurement comes with uncertainty, regardless of precision or accuracy. This is due to two causes: the limitations of the instruments (systematic error) and the expertise of the person taking measurements.

In this context, the term error is the deviation between a measurement and the actual value of a measurement. Because it is difficult to determine the precise or “true” measurement of the quantity, the error in the measurement is rarely established. It is more compatible with NIST methods to measure the degree of uncertainty in a measurement.

Uncertainty refers to the range of values within the accurate measure’s value. This definition is different from the use of other standard terms. For instance, the term accuracy can describe the variation between a measured outcome and its true value. The actual value of a measurement is generally unknown, and the accuracy of a measurement is generally not as sharp. Based on these rules, we changed the way we present lab results. For instance, when students present the outcomes of laboratory tests, they do not compute an error percentage between their measurements and the actual value. Instead, they decide if the acceptable value is within the uncertainties for the range of their results.

Precision Measuring Instruments

Precision Measuring Instruments are devices or tools designed to directly measure physical quantities or measurements indirectly through calculations on objects that are real so that they can give precise measurements.

These instruments comprised tools of a small range that relied on mechanical principles in the past. But, because of the increasing requirement for instruments that can provide exact and fast measurements, some instruments work with pneumatic, electronic and optical principles based on the need and result of the closeness of the measured value.

Mechanical Tools

The primary tools used in mechanics are vernier callipers, micrometre callipers, and various mechanical gauges. Vernier Calipers are used to read scales that go beyond even fractions in the scale. They are made up of an instrument with markings known as the vernier scale. Vernier scale is linked to a slider and the pointer that displays the precise measurements of an object.

Electronic Equipment

Most electronic measurement devices are constructed with this Wheatstone Bridge Circuit, linked to a gauging probe and an indicator, and help us to measure instruments with some uncertainty. They include Multimeters and voltage Testers, Videoscopes, Speedometer Transducers, Capacitance Metres, etc. Electronic equipment can be digital or analogue, as per the requirement.

Conclusion

Precision and accuracy are two essential aspects when making measurements with data. Both accuracy and precision indicate how close an estimate is to the actual value, with some uncertainty. However, while accuracy indicates the degree of accuracy to a recognised or accepted measurement, precision indicates the reproducibility of measurements even if they’re way off from the accepted standard.

The concept of precision, accuracy, and uncertainties is like hitting the bull’s eye. Achieving a precise hit on the target indicates that you are within the middle of your target, even if all marks are on the opposite side from the centre. A precisely hit target means every hit is closely separated, even if they are located far away from where the goal is. Measurements that are precise can be repeated and are very close to the actual value.