I have a naive question about experiment design (I am not a statistician by trade).
Suppose I am doing social psychology, and I am setting up an experiment like Milgram's in the sixties. Do I really have to formulate a quantitative null hypothesis beforehand?
I do not want to re-interpret the results after the fact, hence the soundness of having a clear H0, but at the same time, it might not be immediately clear what H0 should be. After all, this is "exploratory".
In the case of Milgram, apparently what he did was figure out an "expectation" by surveying people about what they thought would happen in the experiment. I can see how you could use that to formulate a very precise H0: the survey gives you an initial distribution, and you can check the real experiment's distribution against the expected one. It becomes quantitative and very precise, significance can be measured.
But is there a concept of an "exploratory" experiment, where it is not known what should happen, and therefore it is difficult to formulate a clear H0? Should we strive to formulate an "arbitrary" H0 in those cases anyway?