Tampering in the context of a controlled process

Process control

Process control is a statistics and engineering discipline that deals with architectures, mechanisms and algorithms for maintaining the output of a specific process within a desired range...

 is when adjustments to the process are made based on outcomes which are within the expected range of variability. The net result is to re-align the process so that an increased proportion of the output is out of specification. The term was introduced in this context by W. Edwards Deming

W. Edwards Deming

William Edwards Deming was an American statistician, professor, author, lecturer and consultant. He is perhaps best known for his work in Japan...

, and he was a strong proponent of using control charts to avoid tampering.