In which research method is the researcher most likely to manipulate variables?

Experimental research is the most appropriate method when it comes to variable manipulation. In this approach, researchers deliberately change or manipulate one or more independent variables to observe the effect on a dependent variable. This manipulation allows for establishing cause-and-effect relationships, as it controls for other variable influences and utilizes random assignment to eliminate bias in the groups being compared.

The strength of experimental research lies in its ability to isolate the effects of the manipulated variables while systematically controlling other factors. This method is foundational in psychology and other sciences, as it provides clear evidence of how changes in certain conditions can lead to variations in outcomes.

In contrast, qualitative research typically focuses on understanding experiences and meanings rather than altering variables. Observational research involves watching and recording behavior without intervention, thus not manipulating any variables. Surveys are designed to gather data through questions and are also not about manipulating variables, but rather about collecting information from participants' responses.