Giving a test "out of age limits" is a problem because you don't have a standardization sample - you can only compare the 4'10" to a 6'. For an example of why this was a problem, my daughter's second grade teacher was very upset because none of her students made "a year's growth" on NWEA, which was 10 points. My 10th grade son told me his score, so I looked it up, and he only needs 3 more points to stay at the 96th percentile next year. So this is the same test, but 2nd graders grow 10 points and high 10th graders 3 points. We know that because we have the standardization sample.
So over those 14 months, between 4'10" to 6, should she grow ten points, or three, or what?
There does tend to be "age equivalents" to "raw scores," which I think aren't affected by the subject being out of age limits. So that's something.
