While it has been said before, a new report published by Policy Analysis for California Education (PACE) says that states like North Carolina exaggerate their test results relative to national standards.

We detail, looking across 12 diverse states, a small improvement in the percentage of children achieving proficiency in reading, based on NAEP results between 1992 and 2005. But states estimated much higher shares of students reaching proficiency, compared with the NAEP results. We then detail how children made greater progress in math proficiency over this 13-year period. Yet again we discovered that state test results exaggerate the annual rate of improvement, compared with the federal NAEP results.

They also point out that states were doing this long before No Child Left Behind.