The FinePointe WBP Controller attempts to correct for drift in the Temperature and Humidity probes by averaging the values of all connected probes during calibration and changing each to match the average value for both Temperature and Humidity.  

However, the system will not allow the Humidity to be modified by more than +/- 4% from its actual reading, and the Temperature cannot be modified by more than +/- 1°C.   

Examples:

If the four probes read Humidity values of 31%, 32%, 33%, and 34%, the average is 32.5% and  all four probe readings will be 32.5% after calibration (applying a 1.5, 0.5, -0.5, and -1.5 offset, respectively). 

If, however, the last probe read a value of 50%, the average would be 36.5% and, due to the  +/- 4% maximum offset, the probe readings would change to 35%, 36%, 36.5%, and 46% (applying a 4, 4, 3.5, and -4 offset, respectively). 

This allows the user to clearly see the potentially inaccurate probe during data collection—the one which is obviously farther from the others—and replace it before recalibrating again.

The same logic is true for the Temperature calibration, but with a maximum offset of +/- 1°C being applied.