Can test vendors keep up with NCLB demands?

It does seem that likely that NCLB demands on test vendors has outstripped their capacity. It is difficult to make tests that stretch high achieving students. Creating high quality tests is expensive and difficult. Sometimes known as the ceiling effect, the inability to measure student learning at the high end can artificially create a situation in which it appears the the gap between two groups of students is closing. Since the upper end of the distribution of scores is bounded, the mean for a higher performing group cannot move up as far or as easily as a lower performing group.

Chris