In a study of aggression in children, the researcher watches a group of children on the playground and records the number of instances of physical or verbal attacks. Which category of measured variable is this researcher using?

Answer: Observational

Explanation: Observational study involves careful and physical observation of events. In this kind of study, the independent variable is not under the control of the experimenter as opposed to experimental study.

In the scenario above, Observational study is used to draw inference from a sample to a population, by recording the number of physical or verbal attacks while the researcher observes. The researcher has no control over the independent variable as he only records what he observes.