não aprofundados

17:28 Sep 28, 2016 

(I'm new here, hello!). I recently translated a nearly identical sentence and while I can't recall the exact phrasing I used without searching for it, I agree with Richard that the implicit value judgements in many of the suggestions change the meaning or emphasis of the original. I think Richard's suggested solution sentence is just fine but an alternate way to phrase it might be:

Scientific studies in this area are few and under-developed.

16:03 Sep 28, 2016 

as I mentioned below, I agree with you we should avoid the negative as much as possible. But that doesn't mean it's forbidden. I mean, sometimes, we have no way out, and the best solution is actually to use a nice little "not", nothing wrong with it. If you can prevent it, so much better. But if you need to use it, you are free to do so, and the translation won't be incorrect, IMO.

12:08 Sep 28, 2016 

Looking at the answers, a lot of these words are loaded, it's true.

'Superficial' can mean false in one sense, but it wouldn't when applied to a scientific study.
'Baseless' is incorrect imo, 'shallow' is negative, 'sketchy' is unclear, then saying what things aren't... maybe a solution would be

There have been very few studies in this area, and none of them have been in-depth.