During a study to measure the effects of violent video games…

During a study to measure the effects of violent video games on aggressive behavior, the researchers learned that a portion of the subjects lived in homes with one or more alcoholic parents. In this study, what type of variable is the “presence of an alcoholic parent”?

In a study about pregnant women’s use of tobacco, the nurse…

In a study about pregnant women’s use of tobacco, the nurse researcher that is collecting the information can link individual subjects’ identities to their responses on a questionnaire but does not share this information with others. What is this is an example of?