I'm not trying to say your child isn't gifted by test like IQ test are calculated in part based on the age of the child. So a child that is learning quickly in the first few years will tend to have a higher IQ then one that does't... it doesn't however mean that they will continue at the same rate. It isn't uncommon for some kids to slow some such that if you test their IQ 2 years later it is somewhat lower than before. I only say that because at 4 years old you run the risk of putting a lot of pressure on a child that might turn out to be normal later and not gifted. You'll find a lot of kids that seem gifted compared to other kids simply because they come from families that have parents that actually interacted with them while they were babies instead of using the TV as a baby sitting service.
So just be careful using numbers from such an early age.
She's not talking about "putting a lot of pressure" on her child; she's talking about not holding her back! BIG difference!
I'm not sure the "TV as babysitter" thing is really relevant. How many of the parents who do that have their kids' IQs tested? Were they likely to be in the test norming groups? I suspect not.
The bigger problem is that before 5-6yo (at the youngest), kids are squirrely about sitting still to take a test. They get bored with the easy questions and stop before they get to the challenging ones. They give wrong answers because its fun to see the tester accept those wrong answers. Some who are very bright haven't started reading yet, and so aren't showing to the best of their ability yet. And so on... Squirrely stuff!
If the child were 2, I'd say that the scores were iffy. By 4, I think you can certainly at least tell GT if you see it. I agree that you can't always tell not-GT yet, but if you think your 4yo is GT, you're probably right. If the scores back what your mom-gut is telling you, then I'd say it's probably pretty certain.
It's certainly true that you might still be unable to tell what *level* of GTness you're dealing with. But I think that if you think your child is GT and the scores back you up, you almost certainly have a GT child.
Holding her back seems dumb to me if she seems ready for school and you think it would be good for her. Much of this has more to do with personality than IQ, though...