The Stanford-Binet test was designed to measure the cognitive ability of both adults and children. It is a revised version of the Binet-Simon test, originally developed by French psychologist Alfred Binet in 1905, when he was commissioned by the French government to develop an assessment to identify children who needed to be placed in special education programs. This initial test was somewhat unreliable, owing to problems with retest accuracy.
The name of the test changed in 1916, when the Stanford University psychologist Lewis Terman revised the Binet-Simon test. This incarnation of the test was widely renowned, and was even used by the American Psychological Association used it to measure the intelligence of Army recruits.
The fifth edition of the Stanford-Binet test has been put through several rigorous reliability tests. A few of these include standard measurement error tests, plotting of the information curves, retest stability of the test. Its internal consistency is reported to be accurate, compared to other IQ assessments.
The IQ scores, as measured by the test, have proven to be stable over time. In addition, the Stanford-Binet test has proven especially precise when it comes to identifying gifted individuals. What's more, people who are re-tested have only shown a small improvement due to familiarity with the test.
It's important to remember that test scores can be influenced by many factors; because of this, more than one instrument may be necessary to properly measure an individual's intelligence. While the Stanford-Binet test is largely accurate, there are instances when the results should be considered invalid.
One of the issues is that a fairly substantial number of preschool children get a score of "0" on the test. This score certainly shouldn't be taken to mean that these children have any profound mental disabilities. Occasionally, a low score can be the result of a lack of cooperation on the part of the child. It is also a difficult test, and has been criticized for being too insensitive to age. Because of some of these reliability issues, the Stanford-Binet test can be readministered after six months.
The test's ability to diagnose mental issues has also come into question. A 2005 study by Dr. Piotrowski that was published in Psychiatric Quarterly also revealed that the Stanford-Binet test should not be used to either diagnose or rule out psychosis. Aside from this downfall, the test mostly remains reliable as a way to measure an individuals cognitive ability.
Overall, the Stanford-Binet test is among the most reliable standardized tests currently used in education. It has undergone many validity tests and revisions.
While there are a few issues with the assessment, most results are treated as accurate--individuals with high scores are usually gifted, and people with low Stanford-Binet scores often face some sort of cognitive disability.