But do give any indications that these are the real causes, or are they also just speculating as so many others do when it comes to explaining those phenomena?

But do give any indications that these are the real causes, or are they also just speculating as so many others do when it comes to explaining those phenomena? Did they study the causes at all? Or did they just note "50% drop out" and then jump to the conclusion that it must be because x? Thanks for translating.