The word "observational" means to watch or look at something closely and carefully in order to gather information or understand what is happening. Full definition
A meta - analysis of observational studies have suggested that planned home birth may be safe and with less interventions than planned hospital birth. (cochranelibrary-wiley.com)
In summer, however, the analysis of observational data coming from weather stations and satellites reveals a clear decrease in the average storm activity. (sciencedaily.com)
First, as a meta - analysis of observational studies, it was prone to biases (eg, recall and selection bias) inherent in the original studies. (academic.oup.com)