Language: Precision vs Accuracy

Motivation

People conflate these words but they are distinct, and I think the distinction is both useful and kind of cool.

In short:

Precision: the degree of refinement with which an operation is performed or a measurement is stated

Accuracy: correctness

Precision has to do with specificity, not necessarily correctness.  Accuracy is all about correctness.

Example 1:

If I said 1 foot is 492.763 millimeters, I would have given you a very precise but inaccurate number.

If I said 1 foot is about 300 millimeters, I would have given you an imprecise, but reasonably accurate approximation.

If I said 1 foot is 304.8 millimeters, I would have given you a precise and accurate number.

Example 2:

If I said the Texas State Capitol building was at latitude/longitude 30.276930, -97.7441325 I have given you a very precise location, but it's not accurate.  It's not correct.  In fact, it's cosmetic surgeon's office.  Notice the red pin in the upper-left:

If I said the Texas State Capitol building was at latitude/longitude 30.275, -97.74 I have given you an accurate location, but the GPS coordinates are of low precision, having only a couple of digits after the decimal place.

If I said the Texas State Capitol building was at latitude/longitude 30.2746742, -97.740345 I have given you accurate, highly precise coordinates for the center of the capitol rotunda.  If you sing in there, it sounds REALLY cool.  It's virtually all marble and granite, so the acoustics are incredible!