Which of these is correct:
'In spite of all that, the effect itself has not been yet extensively studied '
or
'In spite of all that, the effect itself has not been extensively studied yet'
Which of these is correct:
'In spite of all that, the effect itself has not been yet extensively studied '
or
'In spite of all that, the effect itself has not been extensively studied yet'
The first sentence is incorrect, because "yet" cannot stand between "been" and the past participle of the verb (in this case, "studied").
The second sentence is not wrong, since "yet" can go last, after "studied," but it still sounds rather clumsy.
I'd suggest "...has not yet been extensively studied." You can, however, delete "yet" entirely without changing the meaning.