Accuracy & Precision: What's the Difference?

In summary, accuracy refers to how close a measurement or result is to the actual or desired value, while precision refers to how consistent and reproducible a measurement is. Accuracy is about conformity to fact, while precision is about exactness and the number of significant digits in a measurement.
  • #1
thomate1
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What is the difference between accuracy and precision?
 
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  • #2
Hmm, I usually see this as

*"Accuracy"-->how "close" your data/measurement/result is to an exact (more or less) value

*"Precision"-->how "close" your data/measurements/results are to each other. Think of this as a measure of statistical spread and deviation from the mean of your particular data.

E.g., let's say you want to hit a dart-board. You have some darts and you aim at the direct center.

1) Accurate shooting ---> your darts are very close to the center

2) Precise shooting ---> your darts are very close to each other

It is possible to have (low accuracy, high precision), (high accuracy, low precision), (high accuracy, high precision), (low accuracy, low precision).
 
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  • #3
Taken from http://dictionary.reference.com/

Accuracy -

1. Conformity to fact.
2. Precision; exactness.
3. The ability of a measurement to match the actual value of the quantity being measured.

Precision -

1. The state or quality of being precise; exactness.
2a. The ability of a measurement to be consistently reproduced.
2b. The number of significant digits to which a value has been reliably measured.

Claude.
 
  • #4
It's always the very last defintion ... :rolleyes:
 

1. What is the difference between accuracy and precision?

Accuracy refers to how close a measured or calculated value is to the true or accepted value. Precision refers to how close multiple measurements or calculations are to each other.

2. Which is more important, accuracy or precision?

It depends on the specific application. In some cases, accuracy may be more important, while in others, precision may be more critical. For example, in medical testing, accuracy is usually more important, while in manufacturing, precision is often the top priority.

3. How are accuracy and precision measured?

Accuracy is typically measured by comparing a measurement or calculation to a known true or accepted value. Precision is usually measured by calculating the standard deviation or range of multiple measurements or calculations.

4. What are some factors that can affect accuracy and precision?

Some factors that can affect accuracy and precision include human error, instrument calibration, environmental conditions, and the inherent limitations of the measurement or calculation method being used.

5. Can a measurement or calculation be precise but not accurate, or vice versa?

Yes, it is possible for a measurement or calculation to be precise but not accurate, or accurate but not precise. For example, a clock may consistently show the wrong time (not accurate), but it may always be off by the same amount (precise). On the other hand, a dart player may consistently hit the same spot on the dartboard (precise), but it may not be the intended target (not accurate).

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