Gifted Issues Discussion homepage Forums Identification, Testing & Assessment OLSAT scores

I have never put a lot of thought or time (or studying/tutoring) into the OLSATs as they have never mattered to my children (i.e. if you are already in g/t you still take them each year). That said, am curious to know people's thoughts. My DS took the OLSATs 3 years ago and scored somewhere in the 7th stanine across the board, and this year got a perfect score. So my questions are:
1. What are they actually measuring if scores can be that unstable over time with zero work toward them?
2. Does this tell me something about my DS that I don't already know (this is my "sleeper gifted" child who has never done any formal testing)?
Thanks in advance for your thoughts.

It seems to my between an achievement test and an IQ test. What I've seen in my kids though is that their achievement scores progress year to year at a relatively stable rate, but their OLSAT scores were erratic until 3rd/4th grade.