There is no RationalWiki without you. We are a small non-profit with no staff—we are hundreds of volunteers who document pseudoscience and crankery around the world every day. We will never allow ads because we must remain independent. We cannot rely on big donors with corresponding big agendas. We are not the largest website around, butwe believe we play an important role in defending truth and objectivity. | Fighting pseudoscience isn't free. We are 100% user-supported! Help and donate $5, $10, $20 or whatever you can today with  ! |
Accuracy and precision
| Poetry of reality |
 |
| We must know. We will know. |
| A view from the shoulders of giants. |
Accuracy and precision are measurements within science andengineering of how well results fit withreality and how reliable they are.Accuracy is a concept that describes the degree to which ameasurement approximates theactual value, whereasprecision measures howreproducible a result is.
Low accuracy or precision[edit]
An experiment or test with low accuracy or precision is still useful if the other is reasonably high. A test with low precision can be improved withmore samples as each data point will stillaverage out as an accurate value (diagram 1). On the other hand, a test with low accuracy can still be useful if it is precise, because we can conclude that there must be a reproducible and systematic error in the measurement causing the lack of accuracy (diagram 2). In science, this is particularly useful for refining theories and experiments.
Visual representation[edit]
Diagram 1: High accuracy, low precision
Diagram 2: High precision, low accuracy
