How do you define accuracy and precise?

Question

How do you define accuracy and precise?

Answer 1

accuracy is consistent reproducability. precison is consistent predictability. Let's say you shoot a rifle at a target 5 times and all five shots fit inside a circle the size of a quarter, but they are left of the bullseye by 1 inch. The marksman is accurate, but not precise b/c the predicted outcome is what she is aiming at, which is the bullseye. Fedex can deliver packages accurately at 5:10 pm everyday, but since the office is closed - their precision is off.

Answer 2

The dictionary definitions are:

ACCURACY

1.The condition or quality of being true, correct, or exact; freedom from error or defect; precision or exactness; correctness

2.(Chemistry, Physics) The extent to which a given measurement agrees with the standard value for that measurement

3.(Mathematics) The degree of correctness of a quantity, expression, etc

PRECISION

1.a) Accuracy; exactness e.g. to arrive at an estimate with precision

b) Mechanical or scientific exactness e.g. a lens ground with precision

c) Punctiliousness; strictness e.g. precision in one's business dealings

2.(Chemistry, Physics) The extent to which a given set of measurements of the same sample agree with their mean

3.(Mathematics) The degree to which the correctness of a quantity is expressed

From definitions 1) it can be seen that the two terms are almost interchangeable in everyday usage, however, a comparison of definitions 2) and 3) shows their correct scientific usage.

Answer 3

Accuracy is being consistently in the desired location, while precision is being consistently in one location that you're not trying to hit. A good analogy is accuracy being consistently hitting the center of a target, while precision is consistently hitting a spot that isn't the center on a target when you're trying to hit the center.

Answer 4

Actually, Konnor has it upside down.

Precision refers to how close readings are to one another.

Accuracy refers to how close readings are to the true or predicted value.

So, for instance, a device with a systematic error may give very precise readings that are not accurate.

Answer 5

accuracy is how close to the actual amount something is.

precision is how close a set of data are to each other.

so if you measure 10g of a substance to be 9.98g 9.97g and 10.1g you have accuracy because they are all close to the actual amount and you have precision because they are all close to each other

but if you measure 5.45g 5.47g and 5.43g of the same substance you have precision but not accuracy