Hmmm, interesting - especially the quote about the "big joke" at the end 🙂
I remember a similar statistic done a while ago (presented in How to lie with statistics):
Somebody once went to a good deal of trouble to find out if cigarette smokers make lower college grades than non-smokers. It turned out that they did. This pleased a good many people and they have been making much of it ever since. The road to good grades, it would appear, lies in giving up smoking; and to carry the conclusion one reasonable step further, smoking makes dull minds.
This particular study was, I believe, properly done: sample big enough and honestly and carefully chosen, correlation having a high significance, and so on.
The fallacy is an ancient one which, however, has a powerful tendency to crop up in a statistical material, where it is disguised by a welter of impressive figures. It is the one that says that if B follows A, then A has caused B. An unwarranted assumption is being made that since smoking and low grades go together, smooking causes low grades. Couldn't it just as well be the other way around? Perhaps low marks drive students not to think but to tobacco. When it comes right down to it, this conclusion is about as likely as the other and just as well supported by the evidence. But it is not nearly as satisfactory to propagandists.
So, in conclusion, do computers drag on learning? Or is the other way around: students with a tendency to low degrees tend to spend too much time on ICQ or gaming? Or is there a third factor involved?
P.S. By the way, this is a funny book, buy it if you ever see it. Even Brian Kernighan recommends it 🙂