I would use "no conclusive data exist so far".
Student or Learner
I would appreciate your help with the following sentence to make it sound natural:
"Some partial results on ... have been published, but no comprehensive knowledge exists so far."
My problem is the second part of the sentence. Is it OK as it is, or would you prefer "comprehensive knowledge is lacking so far", "there is a lack of comprehensive knowledge so far", "comprehensive knowledge is not available so far"...?
Thanks for your help!
... but our knowledge in this field is still rather limited.