Accuracy vs. Precision

How closely the measured value resembles the true value or the widely accepted reference value is referred to as accuracy. When the same sample is measured repeatedly, precision indicates how well the measured results align each other.

A known volume of a liquid, such as 10 ml, can be pipetted into a graduated cylinder or volumetric flask, and the volume can be measured to show accuracy. Accuracy can be determined by comparing the measured volume to the real volume. The process is regarded as accurate if the measured volume equals the real volume.

The same amount of liquid can be pipetted repeatedly into a graduated cylinder or volumetric flask and the volume can be measured each time to show precision. The precision can then be determined by comparing the measurements. The method is regarded as exact if the measurements are quite near to one another.