IB Chemistry home > Syllabus 2016 > Data Processing > Precision and accuracy

Syllabus ref: 11.1

Every field of learning has its own adopted vocabulary and chemistry is no different. There are very clearly defined meanings to terms that may also be found outside the ambit of chemistry to mean very different things. Precision and accuracy are two such terms.


Precision is measurement that is very consistent in terms of value. If an experiment yields the same, or very similar values time and again it may be said to be precise. This must not be confused with accuracy. If a sharpshooting bowman aims for the centre of a target and always puts the arrow in the same place he is being precise, but inaccurate.




Accuracy refers to how close the results are to the accepted value, or values. Students are usually expected to research the available literature in order to assess the accuracy of experimental results. Students may also be able to obtain theoretical results by calculation.

It may be that there is no information of this kind available, in which case accuracy estimation is not possible.