How is accuracy different from precision

Accuracy refers to the closeness of a measured value to a standard or known value. For example, if in lab you obtain a weight measurement of 3. In this case, your measurement is not close to the known value. Precision refers to the closeness of two or more measurements to each other. Accuracy can be determined by one measurement while many measurements are needed to assess precision.

For instance, by looking at the image above, just by one bullet fired, one knows if it is accurate or not, but a number of attempts have to be fired to tell if the result is precise. Bullets that hit closer to the bullseye are considered more accurate. If a large number of bullets are fired, precision would be the size of the bullet cluster and not how close they are to the bullseye.

In short, we can say that we want all our estimates to hit the target first be accurate to within a certain limit , and then we can concentrate on the precision afterward. The more you work with a specific client, execute on individual projects, and have well defined the tasks, the more precise your scope becomes. In this sense, it is a goal to strive to achieve accuracy as soon as possible, and over time develop precision to scoping your projects.

I hope this has clarified how to use the two terms properly and as always, feel free to contact us for more information. Add some rocket fuel to your projects. Resource Management Manage your bandwidth. Project Management Run successful projects. Team Collaboration Enhance teamwork. Project Accounting Keep the budget insight.

By Industry Agency Scale sustainability. Consulting Organize work. Software Streamline delivery. By Team Operations Refine processes. 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.

Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:. Skip to main content. Introduction to Chemistry. Search for:. Accuracy, Precision, and Error. Learning Objective Describe the difference between accuracy and precision, and identify sources of error in measurement.