Operational Definition

An operational definition describes a behaviour in terms that are so precise that any two observers can watch the behaviour and agree on when it is occurring and when it is not. It strips away subjective labels (like 'angry', 'manipulative', or 'oppositional') and focuses entirely on observable physical actions (e.g., 'screaming louder than conversational volume for more than 3 seconds' or 'striking another person with an open palm').

Writing operational definitions is the critical first step in conducting functional assessments, taking reliable ABC data, and monitoring progress in a Behaviour Intervention Plan (BIP). Without them, data collection becomes subjective and inaccurate.