Which type of study gives the investigator control over experimental conditions?

An experimental study is designed to investigate the effects of one or more independent variables on a dependent variable while allowing the researcher to manipulate or control the conditions of the experiment. This control is essential in establishing a cause-and-effect relationship, as it enables the investigator to isolate the impact of the independent variables from other confounding factors.

In an experimental study, the researcher assigns participants randomly to different groups and applies different treatments or interventions. This structured approach helps minimize biases and variability in the results, leading to more reliable and valid conclusions regarding the relationships among variables.

In contrast, longitudinal studies track the same subjects over a period, observational studies observe subjects in their natural environments without manipulation, and case studies focus on a detailed examination of a single subject or group, lacking the broader controls seen in experimental designs.