Which characteristics are monitored depends upon the measurement protocol. In contrast to the observer, the observed is simply out there, doing what it does, without regard for either the informal observer or the formal scientist. However, once definitions and a measurement regime are in place, the observed rather than the observer is responsible for changes of state. Thus behavior is that part of the observation process that is above and beyond the observer, and therein lies the generality of scientific investigation. Entities and phenomena are both the product of an observer's values and decisions as to what is worthy of further attention.
Science is about predictability, and the predictability derives from models.
Data are limited to the special case of what happened when the measurements were made. Models, on the other hand, subsume data. Only through models can data be used to say what will happen again, before subsequent measurements are made. Data alone predict nothing. Observer and observed both contribute to the scale of phenomena.