Recalibration is the process of ensuring that the data logger or measurement device can produce repeatable and accurate values. The recalibration process involves comparing the digital data logger against another calibrated reference. The two data loggers are placed in an environment where the temperature is varied at specific intervals. Then, the measurements of the two devices are compared. Since one data logger is highly precise, variations in the data logger being tested, if any, will be fixed. CDC states that calibration testing is necessary for Temperature Monitoring Devices (TDMs) every one to two years or according to the manufacturer’s own recommendation.