Possible, certainly. Indeed as we were discussing on some thread recently, it's entirely possible, even common, for someone to score in the top 5% even of an IQ test and then not score in the top 5% of a different IQ test. There is a strong tendency to think as though there is a "fact of the matter" concerning whether or not a given child is gifted - a notion of ur-giftedness, if you like - and there just isn't.
Likely? Correlation is the key here and it's a numerical notion, not one to which the term "infallible" is appropriate. I did recently hear it said that in the upper ranges there was no correlation between OLSAT and IQ tests; I think that must have been an exaggeration. Here is Wren here quoting a slightly more precise statement:
http://giftedissues.davidsongifted.org/BB/ubbthreads.php/topics/7395/OLSAT.htmlIt may seem odd that there could be a correlation between two tests overall but not at some particular level. As a thought experiment: it could be, say, that the very same group of children score above the mean [or, above the 75th percentile or whatever] on two tests, but that within that group of above-average children, knowing the child's score on one test tells you nothing about the child's likely score on the other (besides that it's above the mean, rsp the 75 percentile, which you already knew). This could be the case, for example, if the "basic" questions on the two tests were similar but the "hard" questions on the two were not.
Specifically concerning the tests you mention, I hope someone else knows. I had heard that Raven was well correlated with IQ, that OLSAT isn't in the upper ranges, and I know nothing about CogAT.
