Accuracy

Accuracy is an indication of a measurement's closeness to the accepted value indicated by the relative or percentage error in the measurement. An accurate experiment has low systematic error.

This image outlines the difference between accuracy and precision.

Experimental Error
Experimental error is a measurement of the accuracy of data. It is calculated with"(experimental value - accepted value) / accepted value"Note: experimental error is always positive. If the accepted value is greater than the experimental value, (experimental value - accepted value) is replaced with (accepted value - experimental value).