CHES (Certified Health Education Specialist) Practice Exam 2025 - Free Health Education Specialist Practice Questions and Study Guide

The unique characteristic of experimental trials lies in the manipulation of variables by the researcher. This manipulation involves an active intervention, which is a defining feature of experimental research. In a typical experimental design, the researcher creates conditions to test a hypothesis, often involving a control group and an experimental group. By actively changing one or more independent variables, the researcher observes the effects on one or more dependent variables. This allows for establishing cause-and-effect relationships, which is a key goal in experimental research.

This contrasts with other methodologies, which may not involve such direct manipulation. Non-randomized assignment of participants may occur in observational studies, while a focus on identifying risk factors is common in epidemiological research. Lastly, examining retrospective data only indicates a study design that observes past occurrences without manipulating any variables, distinguishing it from the active nature of experimental trials. Therefore, the ability to manipulate variables to test hypotheses is what sets experimental trials apart from other types of research methodologies.