Hey so, is this a normal thing in meta analyses ?

We identified 46 studies for inclusion in our analysis. Of these, 27 studies reported positive associations (significant links to NDDs), 9 showed null associations (no significant link), and 4 indicated negative associations (protective effects).

27+9+4 is 40 I think ? What happened to the 6 other papers ? I’m always confused by the whole “we ignored half of the studies and we won’t tell you why”, if they can also ignore some of the 46 studies they selected, what does the 46 number mean ?

A blank 10cm by 10cm square piece of aluminium. About 2 cm thick

I think I wanted to know how it felt. Like, the vibe of aluminium