The Hawthorn Effect

The Hawthorn Effect states that short-term improvements will be observed in any human system subject to investigation. Observation of the system leads to a change in the system. However, those short term gains are lost once the system is no longer under investigation.

Note that the Hawthorne Effect does rather complicate attempts to establish a baseline for a process since attempting to establish a baseline leads to improvements in that process. The good news is that if you can establish an improvement over baseline then it is likely to be real since the improvement must be robust to the Hawthorne Effect.