Which of the following defines observational studies?

Observational studies are characterized by the analysis of data collected through observations rather than through controlled experiments or manipulations. These studies do not involve altering scenarios or employing randomization; instead, they observe and record information about a subject as it naturally occurs. This approach allows researchers to gather insights into behaviors, outcomes, or associations without intervening in the studied environment.

In the context of observational studies, the focus is often on examining real-world situations and understanding correlations or patterns that emerge from existing data. This method is particularly useful in fields like epidemiology, social sciences, and market research, where manipulation is not ethical or feasible.

The other choices represent different research methodologies that do not align with the fundamental characteristics of observational studies. For instance, manipulative experiments and hypothesis testing with randomization denote experimental designs aimed at establishing causality, which is distinct from merely observing and recording data as it occurs. Similarly, predictive modeling typically involves using statistical techniques to forecast future events based on current and historical data, rather than strictly studying existing observations.