Usually, the transducer manufacturer performs a unit calibration in their laboratory. The instrumentation engineer should be familiar with the techniques used by the manufacturer to calibrate individual transducers. Experience recommends that the engineer perform an in-house calibration on the individual transducer to verify the accuracy of the manufacturer’s transfer function. If there are deviations from the manufacturer’s transfer function, the engineer may define a new transfer function for that unit, or in some cases, reset the device to conform to the original transfer function. Successive calibrations may indicate upcoming failures. Many engineers stop after performing a transducer calibration. They thencombine the transducer’s transfer function mathematically with the data system signal conditioner’s transfer functions. This provides a calibration estimate under the assumption that the engineer precisely knows all the transfer characteristics of the wiring and other signal conditioning between the transducer and the data storage system. The engineer assumes that all wiring and signal conditioning will function as designed, but one bad connection invalidates the data. Relying solely on transducer calibration is too risky for collection of valid data on an experiment or test.