In choosing appropriate education, it is often needed to compare the ability of a highly gifted child of a younger age with a moderately gifted class of an older age. Before now, this has been basically guesswork.
I have found a better approximation: convert a given IQ at a given age to an absolute measure of intelligence, the Stanford-Binet 5 CSS score or the identical Woodcock-Johnson III or IV W-score, then convert that score back to an IQ score for a given age (or an age for a given IQ score).
Here's my blog post:
Converting IQ at a Given Age to an Absoloute (Rasch) Measure of Intelligence .
Here's the graph that lets you do it:
![[Linked Image from 2.bp.blogspot.com]](http://2.bp.blogspot.com/-tXLt9eo5s6Q/VvlvcmScDkI/AAAAAAAAAMU/Vx12AxqJYcYiGwwNSxFp7jA9mbfqNLcDA/s1600/rasch%2Bintelligence%2Bscore%2Bvs%2Bage%2Bremake%2B1.png)
(which may not work, it's also at the top of the blog post)