IQ classification varies from one publisher to another. IQ tests have poor reliability for determining test-takers' rank order at higher IQ levels, and are perhaps only effective at determining whether a student is gifted rather than distinguishing among levels of giftedness. The Wechsler test manuals have standard score ceilings of 160. However, higher ceilings, including scores into the exceptionally and profoundly gifted range, exist for the WISC-IV and WISC-V, which were specifically normed on large samples of gifted children. Today, the Wechsler child and adult IQ tests are by far the most commonly used IQ tests in hospitals, schools, and private psychological practice. Older versions of the Stanford-Binet test, now obsolete, and the Cattell IQ test purport to yield IQ scores of 180 or higher, but those scores are not comparable to scores on currently normed tests. The Stanford-Binet Third Revision (Form L-M) yields consistently higher numerical scores for the same test-taker than scores obtained on current tests. This has prompted some authors on identification of gifted children to promote the Stanford-Binet form L-M, which has long been obsolete, as the only test with a sufficient ceiling to identify the exceptionally and profoundly gifted, despite the Stanford-Binet L-M never having been normed on a representative national sample. Because the instrument is outdated, current results derived from the Stanford-Binet L-M generate inflated and inaccurate scores. The IQ assessment of younger children remains debated.