Expression: C'est la vie. Pronunciation: [say la vee] Meaning: That's life, Such is life. Register: normal. Notes: The French expression c'est la vie is used far more in English than in French, though unlike many borrowed expressions, the meaning is the same in both languages. C'est la vie is a way of acknowledging something less than ideal that has to be accepted because that's just the way life is..
Two measures of internal validity are treatment integrity and procedural reliability, the extent to which the independent variable was implemented as planned. Social validity refers to the social significance of the target behavior, the appropriateness of the procedures, and the social importance of the outcomes. Assessment of social validity typically includes evaluation of consumer opinion.
External validity is related to generalizing. That's the major thing you need to keep in mind. Recall that validity refers to the approximate truth of propositions, inferences, or conclusions. So, external validity refers to the approximate truth of conclusions the involve generalizations. Put in more pedestrian terms, external validity is the degree to which the conclusions in your study would hold for other persons in other places and at other times. In science there are two major approaches to how we provide evidence for a generalization. I'll call the first approach the Sampling Model.