Is confounding a major threat to internal validity

If the president needed to send two members of the cabinet to italy to negotiate a military treaty, the secretary of defense and the secretary of would most likely be sent.

Psychologists studying infant memory want to determine at what age babies can remember specific events. an experimenter uses several puppets to demonstrate a series of actions while the infant watches. after a delay, the experimenter records how many of the actions the child imitates when playing with the puppets. what is the dependent variable?

What are the cultural characteristics of mexico?