The student `X` takes two measurements and reports the results, as these are 1.95 g & 1.93 g. These values are accurate because they are close to each other, but are not accurate (because they are not close to the actual value) the proximity of an experimental or average value of a series of measurements to the actual value. It is a measure of the difference between the average value and the actual value. Precision expresses the accuracy of the measurement. “The difference between the average value and the actual value is smaller, the accuracy is greater.” Suppose your classmate has measured the width of a standard notebook and shows the result as 8.53 ± 0.08 inches. By declaring uncertainty as 0.08 inches, your classmate confidently asserts that any reasonable measurement of this sheet of paper by other experimenters gives a value of no less than 8.45 inches and no more than 8.61 inches. The experimental error is #”|99.3 °C – 100.0 °C| = 0.7 °C”, the accuracy indicates how closely two or more measurements of the same quantity correspond. It is expressed as a difference between the measured value and the mean. The accuracy indicates the degree of agreement between the measured values. The accepted value is a number or value that scientists and the public consider to be true.

Accuracy refers to the repeatability of the measurement. We must not know the correct or true value. If, for several years, a clock reads every day exactly 10:17, when the sun is at its zenith, this watch is very accurate. As there are more than thirty million seconds in a year, this device is more accurate than a part of a million! It is indeed a very thin watch! You should keep in mind that we don`t have to take into account the complications of time zone edges to decide that this is a good watch. The true meaning of noon does not matter, because we only ensure that the clock gives a reproducible result. A single measurement can be accurate or inaccurate depending on how close it is to the actual value. Suppose you set up an experiment to determine the density of an aluminum metal sample. The accepted value of a measure is the actual or correct value based on general consistency with a reliable reference. For aluminum, the accepted density is 2.70 g/cm 3.

The experimental value of a measurement is the value measured during the experiment. Suppose you determine in your experiment an experimental aluminum density value of 2.42 g/cm3. The error of an experiment is the difference between experimental values and accepted values. [latex]displaystyle %text { Error} =frac{|text{experimental value } -text { accepted value} |} {text{accepted value}} times100%/latex] “The smaller the difference between the value measured by repeated measurements of the same size, the greater the accuracy.” As mentioned above, the more measurements there are, the closer we can get to the actual value of a quantity. With multiple measures (replicates), we can evaluate the accuracy of the results and then use simple statistics to estimate how close the average value would be to the actual value if there were no systematic error in the system. The average differs less from the “actual value” as the number of measurements increases. The accidental error will be smaller with a more accurate instrument (measurements are made in finer steps) and with more repeatability or reproducibility (accuracy). Consider a common laboratory experiment where you need to determine the percentage of acid in a vinegar sample by observing the volume of sodium hydroxide solution needed to neutralize a certain volume of vinegar…