The more I learn about intelligence tests, the more apparent it becomes that we really do not yet understand intelligence at all, let alone high intelligence.
Basically what all the instruments (tests) pretty much break down in predictive reliability when you get near the floors and ceilings. Really, after the 98th%ile and before the 2nd%ile so many threats to internal and external validity just make the tests relatively invalid. Basically at those points you know you have a person/child who is operating very differently from the rest of the population. But exactly what is happening beyond that we don't know yet.
We really don't even know how many children are operating above the 98th%ile on these tests. Researchers are beginning to see evidence that many more people fall in that range than originally thought. So basically that means that the 98th%ile might not actually be the 98th%ile at all!!!!
So, yup, the WPPSI won't give you an IQ. But you really don't need that IQ. You need to know that your child is very highly functioning intellectually. The WPPSI CAN tell you that.
