What Is The Difference Between Accuracy And Precision?


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Julii Brainard Profile
Julii Brainard answered
Accuracy implies truth, or whether an answer or measurement is basically right, given a 'reasonable' margin of error.

Precision is the level of detail in the answer. Typically in science, it means the number of digits, especially after a decimal point.

For instance, you ask me how far it is to the next village. I tell you "About 5 miles". Or I could tell you "4.9323782347348" miles.

About 5 miles is a pretty accurate answer.
But 4.9323782347348 is both accurate, and a very precise answer.

I could also have said "13.29438754 miles". That would be very precise, but not all all accurate -- because the true distance is quite different from 13.3 miles, and not within a reasonable margin of error.

Most of the time in everyday life, we want accuracy and precision is not so useful. In fact, it can be downright annoying to have to deal with all those numbers after the decimal place. But in the engineering and scientific worlds, precision is sometimes almost as essential as accuracy.

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