Accuracy & Precision

Within every calculation made there is a level of error. Tied to this notion of error are the two major principles of precision and accuracy

Experimental Error

Example: Which of the 4 following images is not precise and not accurate?


Example: A student must measure the weight of a sodium bicarbonate compound, NaHCO­3, and obtains the following measurements: 23.12 g, 23.08 g and 23.17g. If the true weight of the compound is 18.01 g what can be said about the student’s results? 

They are accurate and precise.

They are accurate, but not precise.

They are neither accurate or precise.

They are not accurate, but precise.