Difference Between Accuracy and Precision

By: | Updated: Feb-19, 2022
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Something needs to be done accurately, while others need to be precise. The two terms are often used interchangeably, but they actually have different meanings.

In this article, we will look at the difference between accuracy and precision, and when each might be more appropriate.

Accuracy Precision
The degree of correctness of a measurement or calculation. The degree of repeatability of a measurement or calculation.
Used when slight difference in calculation matters a lot. Used when slight difference in calculation doesn’t really matter.

Difference Between Accuracy and Precision

Accuracy is about getting things right. It is the degree of correctness of a measurement or calculation.

For example, if you measure the length of a room and get a result of 10 meters, your accuracy is 1 meter. This means you are correct to the nearest meter.

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Precision, on the other hand, is about getting things the same way each time. It is the degree of repeatability of a measurement or calculation.

For example, if you measure the length of a room 10 times and get results of 10, 10, 10, 10, 10, 10, 10, 10, 10, 10 meters, your precision is 1 meter. This means your measurements are all the same within 1 meter.

So, when do you want accuracy and when do you want precision?

 Accuracy is more important when you are trying to measure something that is important, for example, the length of a room. If you are off by even a little bit, the room may be too short or too long.

Precision is more important when you are trying to measure something that is not important, for example, the length of a table. If the table is off by a few centimeters, it is not going to make a big difference.

Precision can also be used for things like counting. If you want to know how many objects are in a room, it is more important to get the same number each time than it is to measure the objects exactly.

More examples of accuracy and precision includes:

  • The temperature is accurate if it is the same as the actual temperature.
  • The time on a watch is accurate if it is the same as the time on a clock.
  • A scientist may be precise when she reports the results of an experiment, meaning that all her measurements were done the same way and yielded the same results.
  • If you are counting things, you are more precise if you count them multiple times and get the same number each time.

For scientists accuracy is everything but for the rest of us, it depends on the situation. You may need accuracy to make sure your dinner is at the right temperature, but you don’t need precision when you are just cooking for yourself.

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