Cardinals and sin are the realm of religion. Not sure why it's being brought up here.
Choosing a hypothesis after the experiment is run is perfectly valid as long as your experiment is valid for that hypothesis. Besides, you would always run a new experiment again anyway.
So perhaps it's worthwhile to trot out the idea of exploratory vs. confirmatory research.
In exploratory research you collect a bunch of data, and then mine it for interesting associations that might merit further study. It's an essential part of the scientific process, but anything you find from doing it needs to be treated as extremely tentative because it's liable to produce spurious results at least as often as it finds genuine effects.
But that's not what this paper's talking about. It's talking about experiments that are being used to support the approval of new treatments and drugs. That's confirmatory research. In that realm you absolutely must paint the target on the wall before you throw your darts.
Those are ways of looking at it, but experiments have definite structures and that structure can be exploited to create experiments that potentially reveal more information than another experiment.
If the experiment is constructed correctly, it can support validation of multiple hypotheses.
I would completely believe that most experimentation being performed currently is not structured to make further exploitation possible.
I should have clarified that statement as I don't think it's quite correct.
It should read:
I would completely believe that most experimentation being performed currently is not structured to make further exploitation, of the type desired/wished, possible.
There are almost certainly facts available that are not discovered/discussed from past experiments. Many of them are likely trivial and/or not what researchers would wish or hope that their data could tell them. However, they can still be mined.
In any case though, you would still re-run experiments to further validate/reject the hypotheses. That is simply basic science.
Yes, you can always choose any hypothesis you want. It's largely irrelevant.
Every experiment will support analysis through a set of hypotheses. Just because you didn't select all of those hypotheses before the experiment ran doesn't mean you can't select it after the experiment.
Imagine that an experiment has been run, but you do not know the results (or even what was done). Now you select a hypothesis, if the experiment required to validate the hypothesis is the same as what was run previously, you can now look at and use the results.
A hypothesis is like running a query against a database. Many queries are valid, even though the data may not have changed.
>Otherwise, why are you re-running it?
Science requires it. Doctrine from one-off experimentation is religion (hard to dump).
It's fine if you run a separate experiment to justify the hypothesis. If you choose the hypothesis after conducting the experiment, then the p-values you obtain for that hypothesis are invalid.
Choosing a hypothesis after the experiment is run is perfectly valid as long as your experiment is valid for that hypothesis. Besides, you would always run a new experiment again anyway.