the average IQ in the U.S. is 98

[gordianot]

141. The tests are often revised some questions change.

I once attended a rare lecture by David Wechsler. It was in the early 1990's. He authored the Wechsler Scale spoke with nostalgia for many test questions those retained and discarded as well as the statistical methods. A really fascinating man with a lot of insight into people. Each edition is different some of the questions are retained because they are popular and give insight into people. The statistical methods also vary testing questions across a wide variety of American populations. In an effort to be culture free what you end up is an aggregate multi group score the examiner has some latitude selecting various norms. There has been some interest reviving old test for comparison with modern groups I do have specifics but understand that eye, hand, motor planning among children today has greatly increased. There are some who attribute this to technology. Generally test publishers note a 3 point improvement from a standard mean every 4 years in Industrial countries. Plans for test revisions are on going.