Standards and controls are used to evaluate the effectiveness of an analytical method. They might be reference solutions or test solutions. To calibrate the equipment or reagents used in a laboratory test, a standard is a sample with a known concentration or value. A control sample is one that has a known or anticipated value and is used to assess how well a laboratory test is working. Controls are run concurrently with patient samples to make sure the test is operating properly and to look for any faults or issues.