Complex sentence: Research conducted at the Jewish Theological Seminary of America showed that NETA was not effective for students with learning disabilities, but there has not yet been a comprehensive study as to NETA's effectiveness for students without a learning disability.
Split into simpler sentences: Research conducted at the Jewish Theological Seminary of America showed that NETA was not effective for students with learning disabilities. The Jewish Theological Seminary study also mentions that there has not yet been a comprehensive study as to NETA's effectiveness for students without a learning disability.