Which of the following is TRUE?
Group of answer choices
External validity deals with the problem of projecting one's results from the experimental setting to the real world .
External validity is concerned with the issue of whether or not the specific treatment in which the researchers are interested has actually brought about the effect they have observed .
a and c
a, b, and c
A consumer good purchase experiment conducted in a mock-up store is more externally valid than the same experiment in a real store setting .