Precision and Accuracy in Measurement

Conducting a chemistry experiment often requires a scientist to make several different measurements during the course of the experiment.  Unfortunately, each measurement will have some error.  How much error there is depends on several factors, such as the skill and attention to detail of the scientist, the instrument being used, and the design of the experiment.  How reliable the measurement is depends upon two factors:  the accuracy and the precision.  Precision refers to how closely measurement agree to each other (ie.  How consistent measurements are.)  Accuracy refers to how well measurements agree with the accepted or actual value (ie. How correct measurements are.)