Observational data refers to

Observational data is data that has been collected through observation. It can include information gathered through direct observation, either through human or machine observation, or through indirect observation such as surveys or other data collection methods. Observational data can be used for descriptive and explanatory purposes, as it provides an insight into relationships between variables or trends in the natural or man-made environment.

facts and figures obtained by watching, either mechanically or in person, how people actually behave.