Calibration of scientific instruments, such as thermometers and pipettes, ensures that these instruments provide the accurate results needed. In medicine, the standard of patient care requires accurate instrumentation. In scientific research, instrument calibration, traceable to ISO standards, allows others to recreate the experiment in order to verify results.
Candy makers are aware that the thermometers they use change over time. A shift of only 5 degrees is enough to result in a failed batch of candy. In the modern laboratory, many instruments are electronic in nature.
According to the National Instrument Corporation, "The accuracy of electronic components used in all instruments naturally drifts over time." Calibrating and adjusting an instrument corrects for such electronic drift, ensuring accuracy. Non-electronic instruments also change over time. Good laboratory procedure calls for calibration of all new instruments and recalibration at regular intervals. Instruments used regularly often require recalibration after a specified number of operating hours. Proper procedure also requires calibration of instruments subject to abnormal shock or vibration. In addition, questionable results call for recalibration. Some instruments allow the user to make adjustments to ensure the instrument delivers an accurate amount. Once the adjustment is complete, the user recalibrates the device. In other cases, out-of-adjustment instruments require factory repair or replacement.