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Internal validity is the validity that occurs within an experiment. Internal validity focuses on the variables and how they manipulate the experiment. To be sure that an experiment has internal validity, there has to be a certain amount of control to prevent as many outside factors as possible from interfering. This can be done in the form of safeguards like having the experiment done in a controlled environment. (Myers & Hanson, 2012). External validity is the amount of generalization that can be done so that an experiment can pertain to many types of people. To increase external validity, an experiment must use skills like aggregation, to analyze data in different ways (Myers & Hanson, 2012).