# Accuracy and precision

What is the difference between accuracy and precision?

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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).

Last edited:
Claude Bile
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.

It's always the very last defintion ...