An observational study is best described as which of the following?

• A. A study that observes subjects and records data without manipulating variables
• B. An experiment where researchers assign treatments
• C. A survey with questions
• D. A randomized controlled trial

Answer: (A)

An observational study is defined by watching subjects and recording data without manipulating variables. Researchers do not assign treatments or intervene; they simply observe natural variations and collect outcomes. This contrasts with an experimental design where treatments are assigned by the researchers, such as in randomized controlled trials. A survey can be a data-collection method within observational research, but the defining feature is the lack of intervention. Observational studies can reveal associations, but they’re more limited for proving causation due to potential confounding factors.