Which analysis method involves observing events as they happen?

Prospective analysis is focused on observing events as they occur in real-time or in the future. This method allows researchers or practitioners to gather data directly during the event, leading to more accurate and immediate insights. For instance, in a medical context, prospective analysis might involve monitoring patients' responses during a treatment or procedure as it unfolds, which can provide valuable information on outcomes and efficacy.

This analysis is distinct from retrospective analysis, which looks back at past events and data, and descriptive analysis, which summarizes historical data without necessarily observing or analyzing ongoing events. Predictive analysis, on the other hand, uses historical data to make educated guesses about future outcomes rather than observing current events directly. Thus, the key aspect of prospective analysis lies in its real-time observation and data collection.