Wikipedia is useless
...at least sometimes it is. Take this gem, for example:
In probability theory and statistics, the probit function is the inverse cumulative distribution function (CDF), or quantile function associated with the standard normal distribution. It has applications in exploratory statistical graphics and specialized regression modeling of binary response variables.
A well-trained statistician will be perfectly able to understand the above, and perhaps fix any errors in it. However, anyone who isn't a highly trained statistician will not; and a trained statistician probably doesn't even need wikipedia to know the above.
I did get some basic statistics during my last studies, and have an understanding of some of the basic terms and concepts of statistics. Yet the above makes no sense to me, at all.
As an example, consider the familiar fact that the N(0,1) distribution places 95% of probability between -1.96 and 1.96, and is symmetric around zero. It follows that
... Or something. Suuuure.
(posted belatedly because my server was down yesterday)
I agree that some Wikipedia articles are pretty obscure, but I am not sure if this is a good example. Probit is a pretty technical term in statistics, not a basic concept; I don't see how it could be useful outside of the statistical world, and moreover, I don't think you can expect it to be defined so that anyone (or even anyone with "basic statistics") can understand it.
A trained statistician (or a trained person in any field, for that matter) does not know or remember everything by heart, so an entry like this is likely to be useful anyway. Anyway, in the case of the probit, is is a problem of the concept finding its right audience, and I don't think Wikipedia is to blame here.
As for the rest of the example (the part with the Phi function), it is usually accompanied by a figure showing the normal distribution and indicating what Phi means; this is a basic concept of statistics, but one that is not easy to really grasp. Here, the Wikipedia entry could be improved.
Zorglub