Question

What is the difference between internal validity and external validity​? A. A statistical analysis is said to have internal validity if the statistical inferences about causal effects can only be verified by a few researchers. The analysis is said to have external validity if conclusions can be verified by many researchers. B. A statistical analysis is said to have external validity if the statistical inferences about causal effects are valid for the population being studied. The analysis is said to have internal validity if conclusions can be generalized to other populations and settings. C. A statistical analysis is said to have internal validity if the statistical inferences about causal effects are valid for the population being studied. The analysis is said to have external validity if conclusions can be generalized to other populations and settings. D. Internal validity and external validity are equivalent.

Answer 1

C. A statistical analysis is said to have internal validity if the statistical inferences about causal effects are valid for the population being studied. The analysis is said to have external validity if conclusions can be generalized to other populations and settings.

So internal validity means the results are accurate and you can use them to make sense of the group you are studying. External validity still means the results are accurate, but that you can use them to make assumptions about the population as a whole.

So if you look at a field of cows where half are white and half are brown, you have internal validity that 50% of your sample is white and 50% is brown. This result would not have external validity because in the whole world, cows can be different colors or combinations of colors.