To clarify the question, what kind of scientific experiment would you even imagine that would even resemble something producing evidence for or against free will?
(These experiments talked about in this topic do not at all fit it: they just show that there are conscious and subconscious parts of our experience of life and our experience of the process of choice. In what world would that be related to the degree of "free-ness" of that choice is beyond me. I thought we all knew already that there are conscious and subconscious parts of the brain and that many of activities of "I" are subconscious.)