Specific conditions, events, or activities that we want to observe determine the observational reporting system (and correspond to measurement questions). To specify the observation content, we should include both the major variables of interest and any other variables that may affect them. From this cataloging, we then select those items we plan to observe. For each variable chosen, we must provide an operational definition if there is any question of concept ambiguity or special meanings. Even if the concept is a common one, we must make certain that all observers agree on the measurement terms by which to record results. For example, we may agree that variable W will be reported by count, while variable Y will be counted and the effectiveness of its use judged qualitatively.