Some process controls are not very critical but many, many are--particularly when a process is operating near a tipping point where it could get out of control quickly if not well monitored. Entire production batches have been lost or suffered reduced reliability when critical parameters were not kept within narrow limits. The precision resistor used in the analog sensor has a major impact on the performance and reliability of monitoring and control circuits. The resistor's long-term stability, robustness against ESD, and resistance to moisture are all factors that need to be taken into consideration.