Which method provides a record of behavioral observations over time without systematic intervention?

The concept of baseline is fundamental in behavior analysis and research settings, particularly in the context of tracking behavioral changes over time. Establishing a baseline involves observing and recording an individual’s behavior under natural conditions without introducing any systematic intervention or therapy. This allows for a clear understanding of the individual's typical behavior patterns before any changes are implemented.

By documenting the behavior consistently over a specified period, practitioners can identify trends or patterns in behavior that will serve as a comparison point when interventions are later introduced. This method is essential for measuring the effectiveness of interventions, as it provides a point of reference to determine whether any observed changes are due to the intervention or simply part of the individual's normal variability.

In contrast, options like interval time sampling and planned activity checks involve systematic methods of observing behavior during specific activities or predefined intervals, which inherently include structured interventions or frameworks. Behavior therapy, on the other hand, involves active intervention strategies aimed at changing behavior, which again makes it different from a purely observational baseline. Hence, the baseline method is the correct choice, as it focuses solely on observation without intervention.