Final answer:
The site placement criterion addressing the concern of observer influence in an operation is observer bias, which is mitigated by maintaining unobtrusiveness and utilizing inter-rater reliability.
Step-by-step explanation:
The site placement criterion that considers the concern of a well-placed observer potentially compromising the entire operation is observer bias. When conducting observational research, it is critical to maintain unobtrusiveness to ensure that subjects behave naturally. To mitigate observer bias, clear criteria for recording behaviors must be established and multiple observers should be used to test inter-rater reliability, which assesses the consistency of observations by different observers. The presence of an observer can influence behavior, much like how one's driving behavior may change if they are aware that a police car is following them. Therefore, the observer's placement and role, whether as a non-participant or participant observer, must be planned with care to avoid altering the subjects' behavior and to obtain reliable data.