Which type of variable is neither manipulated nor measured as the outcome in an experiment?

In the context of experimental research, an extraneous variable refers to any variable that is not the focus of the study but may still influence the results. These variables can introduce unwanted variability, potentially confounding the relationship between the independent and dependent variables. They are not directly manipulated or measured in the study, which is why they do not fit into the categories of independent or dependent variables.

The key characteristic of extraneous variables is that they are typically present in the environment or the sample being studied and can impact the outcomes without being the primary focus of the investigation. Identifying and controlling for extraneous variables is essential for maintaining the internal validity of an experiment, ensuring that the observed effects can be attributed to the manipulation of the independent variable rather than other unmeasured factors.