What is the difference between accuracy and precision in chemistry

You carry out the experiment and obtain a value. Just to be on the safe side, you repeat the procedure on another identical sample from the same bottle of vinegar. If you have actually done this in the laboratory, you will know it is highly unlikely that the second trial will yield the same result as the first. In fact, if you run a number of replicate that is, identical in every way trials, you will probably obtain scattered results. With multiple measurements replicates , we can judge the precision of the results, and then apply simple statistics to estimate how close the mean value would be to the true value if there was no systematic error in the system.

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Skip to main content. Introduction to Chemistry. Search for:. A classic way of demonstrating the difference between precision and accuracy is with a dartboard. Think of the bulls-eye center of a dartboard as the true value.

The closer darts land to the bulls-eye, the more accurate they are. Question Set:. An oceanographer needs to go out in a boat to collect an important temperature and salinity data logger that is attached to an underwater buoy. How does each of the following situations illustrate the differences between precision and accuracy? The oceanographer checks the weather forecast the night before her trip so she knows what to wear on the boat. The other GPS units belonging to her colleagues on the boat also indicate that they are at the correct location.

After an extensive search, the oceanographer finds the buoy 50 meters m from the boat. While on the way back to shore, the oceanographer throws in a fishing line to see if she can catch anything for dinner. She is lucky enough to catch a mahi-mahi.

When she pulls it out of the water, her colleagues estimate the weight of the fish. Their estimates are When they weigh the fish upon returning to shore, the actual weight is The terms Accuracy and Precision are critical within science and their meanings are constantly being used incorrectly or misunderstood to mean the same thing. At Precisa, our work is centred on the production of Precision measurements.

This article aims to clear up the confusion, exploring the difference between precision and accuracy and the correct way to use each term, using the example of a dart board to demonstrate. It is possible for precision measurements to not be accurate. Both accuracy and precision reflect how close a measurement is to an actual value, but they are not the same.

Accuracy reflects how close a measurement is to a known or accepted value, while precision reflects how reproducible measurements are, even if they are far from the accepted value.