What type of study involves gathering data on existing conditions without intervention?

An observational study is characterized by the collection of data without the researcher intervening or manipulating any variables. In this type of study, researchers observe and gather information about subjects in their natural settings to identify patterns, relationships, or associations among variables. This is crucial in situations where ethical or practical considerations prohibit experimentation, allowing researchers to draw insights from real-world conditions.

While both longitudinal and cross-sectional studies fall under observational studies, they have distinct characteristics. Longitudinal studies involve repeated observations of the same variables over a long period, tracking changes over time, whereas cross-sectional studies provide a snapshot of data at a single point in time. Thus, while all of these study types relate to gathering data, only the observational study explicitly highlights the absence of researcher intervention, making it the correct answer for understanding existing conditions as they are.