Which research method involves manipulating key factors to observe effects on behavior?

The research method that involves manipulating key factors to observe effects on behavior is experimental research. This method is specifically designed to establish cause-and-effect relationships by systematically changing one variable (the independent variable) while controlling others. Researchers observe how these manipulations influence outcomes (the dependent variables), which allows them to draw conclusions about the effects of changes.

In experimental research, participants are typically divided into different groups, and each group experiences a different level or type of the independent variable. By this design, researchers can more confidently attribute changes in behavior or outcomes directly to the manipulations they implemented, rather than to other factors. This methodological rigor is what distinguishes experimental research from other types such as qualitative, descriptive, or correlational research. Qualitative research focuses on understanding behaviors and experiences through non-numerical data, and descriptive research provides a snapshot of a phenomenon without establishing causal relationships. Correlation research, on the other hand, identifies relationships between variables but does not manipulate them, making it less effective for establishing causal links.