A tall order, but without such a measure, we can predict that in about five years NAEP scores will not have moved much, and the mutterings will begin. In another five years we’ll have bounced on to the next fix.
I think there is good reason to think NAEP scores will go up, because the Common Core assessments are likely to be more closely aligned with NAEP, and thus test prep for Common Core will be more directly relevant to preparation for NAEP.
The more alignment there is, the less data. If graduation is based on achievement on Common Core assessments, college admissions and the difficulty of entry-level college courses aligned to CCRS, NAEP and Common Core assessments in alignment, then test scores, grad rates, and college enrollment and success rates should converge, which will lead to fewer checkpoints on the real preparedness of students, not more.